Remove linting from release pipelines 🧹

This might be a controversial choice but I think our release Pipelines
should only include Tasks that we expect to give us useful feedback
about the release.

Linting should never fail on a release Pipeline since any issues should
be caught in the PR and
tektoncd/plumbing#241 is making linting
flakey.

I also made it so build and unit test can run in parallel since neither depends
on the other.

I tested this by manually applying the pipelines and manually triggering
the nightly cron:

```
 k --context dogfood create job --from cronjob/nightly-cron-trigger-pipeline-nightly-release nightly-cron-trigger-pipeline-nightly-release-manual-03232020
```

tekton/README.md

@@ -186,7 +186,6 @@ Install Task from plumbing too:
 
 ```bash
 # Apply the Tasks we are using from the catalog
-kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/golang/lint.yaml
 kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/golang/build.yaml
 kubectl apply -f https://raw.githubusercontent.com/tektoncd/catalog/master/golang/tests.yaml
 kubectl apply -f https://raw.githubusercontent.com/tektoncd/plumbing/master/tekton/resources/release/

tekton/release-pipeline-nightly.yaml

@@ -39,22 +39,7 @@ spec:
   - name: notification
     type: cloudEvent
   tasks:
-    - name: lint
-      taskRef:
-        name: golangci-lint
-      params:
-        - name: package
-          value: $(params.package)
-        - name: version
-          value: v1.21
-        - name: flags
-          value: "-v --timeout 10m"
-      resources:
-        inputs:
-          - name: source
-            resource: source-repo
     - name: unit-tests
-      runAfter: [lint]
       taskRef:
         name: golang-test
       params:
@@ -65,7 +50,6 @@ spec:
           - name: source
             resource: source-repo
     - name: build
-      runAfter: [lint]
       taskRef:
         name: golang-build
       params:

tekton/release-pipeline.yaml

@@ -57,23 +57,7 @@ spec:
             resource: bucket
           - name: source-to-release
             resource: source-repo
-    - name: lint
-      runAfter: [precheck]
-      taskRef:
-        name: golangci-lint
-      params:
-        - name: package
-          value: $(params.package)
-        - name: flags
-          value: -v
-        - name: version
-          value: v1.21
-      resources:
-        inputs:
-          - name: source
-            resource: source-repo
     - name: unit-tests
-      runAfter: [lint]
       taskRef:
         name: golang-test
       params:
@@ -86,7 +70,7 @@ spec:
           - name: source
             resource: source-repo
     - name: build
-      runAfter: [lint]
+      runAfter: [precheck]
       taskRef:
         name: golang-build
       params: