[receiver/vcenter] Adds vCenter VM CPU readiness metric (#33608)

**Description:** <Describe what has changed.>
<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
This PR adds the `vcenter.vm.cpu.readiness` metric.
More information on this metric can be found
[here](https://vdc-repo.vmware.com/vmwb-repository/dcr-public/d1902b0e-d479-46bf-8ac9-cee0e31e8ec0/07ce8dbd-db48-4261-9b8f-c6d3ad8ba472/vim.vm.Summary.QuickStats.html).
**Link to tracking Issue:** #33607

**Testing:** <Describe what testing was performed and which tests were
added.>
The metric was scraped from a test vCenter environment, and golden test
files were updated to reflect the addition of the metric.

**Documentation:** <Describe the documentation added.>
Documentation was updated according to the metadata.yaml

.chloggen/add_vcenter_vm_cpu_readiness_metric.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: vcenterreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Adds vCenter CPU readiness metric for VMs." 
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33607]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

.chloggen/drop_support_for_vcenter_6.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: breaking
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: vcenterreceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: "Drops support for vCenter 6.7" 
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [33607]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: [user]

receiver/vcenterreceiver/README.md

@@ -20,7 +20,6 @@ This receiver has been built to support ESXi and vCenter versions:
 
 - 8
 - 7.0
-- 6.7
 
 A “Read Only” user assigned to a vSphere with permissions to the vCenter server, cluster and all subsequent resources being monitored must be specified in order for the receiver to retrieve information about them.
 

receiver/vcenterreceiver/documentation.md

@@ -477,6 +477,24 @@ As measured over the most recent 20s interval.
 | ---- | ----------- | ------ |
 | object | The object on the virtual machine or host that is being reported on. | Any Str |
 
+## Optional Metrics
+
+The following metrics are not emitted by default. Each of them can be enabled by applying the following configuration:
+
+```yaml
+metrics:
+  <metric_name>:
+    enabled: true
+```
+
+### vcenter.vm.cpu.readiness
+
+Percentage of time that the virtual machine was ready, but could not get scheduled to run on the physical CPU.
+
+| Unit | Metric Type | Value Type |
+| ---- | ----------- | ---------- |
+| % | Gauge | Int |
+
 ## Resource Attributes
 
 | Name | Description | Values | Enabled |

receiver/vcenterreceiver/internal/metadata/testdata/config.yaml

@@ -49,6 +49,8 @@ all_set:
       enabled: true
     vcenter.resource_pool.memory.usage:
       enabled: true
+    vcenter.vm.cpu.readiness:
+      enabled: true
     vcenter.vm.cpu.usage:
       enabled: true
     vcenter.vm.cpu.utilization:
@@ -156,6 +158,8 @@ none_set:
       enabled: false
     vcenter.resource_pool.memory.usage:
       enabled: false
+    vcenter.vm.cpu.readiness:
+      enabled: false
     vcenter.vm.cpu.usage:
       enabled: false
     vcenter.vm.cpu.utilization:

receiver/vcenterreceiver/metadata.yaml

@@ -441,6 +441,15 @@ metrics:
       value_type: int
       aggregation_temporality: cumulative
     attributes: []
+  vcenter.vm.cpu.readiness:
+    enabled: false
+    description: Percentage of time that the virtual machine was ready, but could not get scheduled to run on the physical CPU.
+    unit: "%"
+    gauge:
+      value_type: int
+    attributes: []
+    warnings:
+      if_enabled_not_set: "this metric will be enabled by default starting in release v0.105.0"
   vcenter.vm.memory.utilization:
     enabled: true
     description: The memory utilization of the VM.

receiver/vcenterreceiver/metrics.go

@@ -140,6 +140,10 @@ func (v *vcenterMetricScraper) recordVMStats(
 		return
 	}
 	v.mb.RecordVcenterVMCPUUtilizationDataPoint(ts, 100*float64(cpuUsage)/float64(cpuLimit))
+
+	cpuReadiness := vm.Summary.QuickStats.OverallCpuReadiness
+	v.mb.RecordVcenterVMCPUReadinessDataPoint(ts, int64(cpuReadiness))
+
 }
 
 var hostPerfMetricList = []string{

receiver/vcenterreceiver/scraper_test.go

@@ -39,6 +39,7 @@ func TestScrapeConfigsEnabled(t *testing.T) {
 	defer mockServer.Close()
 
 	optConfigs := metadata.DefaultMetricsBuilderConfig()
+	optConfigs.Metrics.VcenterVMCPUReadiness.Enabled = true
 
 	cfg := &Config{
 		MetricsBuilderConfig: optConfigs,

receiver/vcenterreceiver/testdata/metrics/expected-all-enabled.yaml

@@ -5212,6 +5212,14 @@ resourceMetrics:
             stringValue: CentOS 9
     scopeMetrics:
       - metrics:
+          - description: Percentage of time that the virtual machine was ready, but could not get scheduled to run on the physical CPU.
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: vcenter.vm.cpu.readiness
+            unit: '%'
           - description: The amount of CPU used by the VM.
             name: vcenter.vm.cpu.usage
             sum:
@@ -5841,6 +5849,14 @@ resourceMetrics:
             stringValue: CentOS 7
     scopeMetrics:
       - metrics:
+          - description: Percentage of time that the virtual machine was ready, but could not get scheduled to run on the physical CPU.
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: vcenter.vm.cpu.readiness
+            unit: '%'
           - description: The amount of CPU used by the VM.
             name: vcenter.vm.cpu.usage
             sum:
@@ -6470,6 +6486,14 @@ resourceMetrics:
             stringValue: CentOS 8
     scopeMetrics:
       - metrics:
+          - description: Percentage of time that the virtual machine was ready, but could not get scheduled to run on the physical CPU.
+            gauge:
+              dataPoints:
+                - asInt: "0"
+                  startTimeUnixNano: "1000000"
+                  timeUnixNano: "2000000"
+            name: vcenter.vm.cpu.readiness
+            unit: '%'
           - description: The amount of CPU used by the VM.
             name: vcenter.vm.cpu.usage
             sum: