Windows CI: Upload test results to AZP (#14083)

- Requires removing --output_base flag to Bazel startup options
- The TEST_TMPDIR and BUILD_DIR bind mounts from the host are where
  Bazel will place build output etc.
- Allowing Bazel to place build and test output there will give the host
  access to the data to upload

Signed-off-by: Sunjay Bhatia <sunjayb@vmware.com>
Co-authored-by: William A Rowe Jr <wrowe@vmware.com>

.azure-pipelines/pipelines.yml

@@ -393,6 +393,12 @@ stages:
               BAZEL_REMOTE_CACHE: grpcs://remotebuildexecution.googleapis.com
               BAZEL_REMOTE_INSTANCE: projects/envoy-ci/instances/default_instance
               GCP_SERVICE_ACCOUNT_KEY: $(GcpServiceAccountKey)
+          - task: PublishTestResults@2
+            inputs:
+              testResultsFiles: "**/bazel-out/**/testlogs/**/test.xml"
+              testRunTitle: "windows"
+              searchFolder: $(Build.StagingDirectory)/tmp
+            condition: always()
           - task: PublishBuildArtifacts@1
             inputs:
               pathtoPublish: "$(Build.StagingDirectory)/envoy"

bazel/README.md

@@ -126,14 +126,19 @@ for how to update or override dependencies.
     Install bazelisk in the PATH using the `bazel.exe` executable name as described above in the first section.
 
     When building Envoy, Bazel creates very long path names. One way to work around these excessive path
-    lengths is to change the output base directory for bazel to a very short root path. The CI pipeline
-    for Windows uses `C:\_eb` as the bazel base path. This and other preferences should be set up by placing
+    lengths is to change the output base directory for bazel to a very short root path. An example Bazel configuration
+    to help with this is to use `C:\_eb` as the bazel base path. This and other preferences should be set up by placing
     the following bazelrc configuration line in a system `%ProgramData%\bazel.bazelrc` file or the individual
     user's `%USERPROFILE%\.bazelrc` file (rather than including it on every bazel command line):
+
     ```
     startup --output_base=C:/_eb
     ```
 
+    Another option to shorten the the output root for Bazel is to set the `USERNAME` environment variable in your shell
+    session to a short value. Bazel uses this value when constructing its output root path if no explicit `--output_base`
+    is set.
+
     Bazel also creates file symlinks when building Envoy. It's strongly recommended to enable file symlink support
     using [Bazel's instructions](https://docs.bazel.build/versions/master/windows.html#enable-symlink-support).
     For other common issues, see the

ci/windows_ci_steps.sh

@@ -42,7 +42,7 @@ export TEST_TMPDIR=${BUILD_DIR}/tmp
 
 [[ "${BUILD_REASON}" != "PullRequest" ]] && BAZEL_EXTRA_TEST_OPTIONS+=(--nocache_test_results)
 
-BAZEL_STARTUP_OPTIONS+=("--output_base=c:/_eb")
+BAZEL_STARTUP_OPTIONS+=("--output_base=${TEST_TMPDIR/\/c/c:}")
 BAZEL_BUILD_OPTIONS=(
     -c opt
     --show_task_finish