Attempt to trigger Azure pipelines on merge queue events (#9809)

* Attempt to trigger Azure pipelines on merge queue events

This commit attempts to add a trigger condition to our azure pipelines
job to trigger on commits to the gh merge queue branch.

* Only trigger PR CI in queue, not push CI

---------

Co-authored-by: Jake Lishman <jake.lishman@ibm.com>
(cherry picked from commit b047a7c)

azure-pipelines.yml

@@ -8,6 +8,7 @@ trigger:
     include:
       - 'main'
       - 'stable/*'
+      - 'gh-readonly-queue/*'
   tags:
     include:
       - '*'
@@ -130,8 +131,10 @@ stages:
                 id: 7864
                 comment: Nightly test job failed at commit $(Build.SourceVersion).  View the logs at $(System.TeamFoundationCollectionUri)$(System.TeamProject)/_build/results?buildId=$(Build.BuildId).
 
-  # Full PR suite.
-  - ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
+  # Full PR suite.  This also needs to apply to the merge queue, which appears
+  # as a push event.  The queue won't get cron triggered because the schedule
+  # trigger doesn't have it as a target.
+  - ${{ if or(eq(variables['Build.Reason'], 'PullRequest'), contains(variables['Build.SourceBranch'], 'gh-readonly-queue')) }}:
     # The preliminary stage should be small in both total runtime (including
     # provisioning) and resources required.  About half of PR commits result in
     # a CI failure, and over 90% of these are in linting, documention or a test
@@ -191,9 +194,9 @@ stages:
           parameters:
             pythonVersion: ${{ parameters.maximumPythonVersion }}
 
-  # Push to main or the stable branches.  The triggering branches are set in the
-  # triggers at the top of this file.
-  - ${{ if and(eq(variables['Build.Reason'], 'IndividualCI'), startsWith(variables['Build.SourceBranch'], 'refs/heads/')) }}:
+  # Push to main or the stable branches.  The triggering branches also need to
+  # be in the triggers at the top of this file.
+  - ${{ if and(eq(variables['Build.Reason'], 'IndividualCI'), or(startsWith(variables['Build.SourceBranch'], 'refs/heads/main'), startsWith(variables['Build.SourceBranch'], 'refs/heads/stable/'))) }}:
     - stage: "Push"
       jobs:
         - template: ".azure/test-linux.yml"