Disabling source-build build leg in PR validation

.vsts-ci.yml

@@ -369,15 +369,18 @@ stages:
       parameters:
         vmrBranch: ${{ parameters.vmrBranch }}
 
+# TODO: Disable source-build builds in PR validation until source-build is more sustainable
+# Tracking issue: https://github.com/dotnet/source-build/issues/3214
+#
 # In case the VMR Build stage needs to be temporarily disabled, please make sure that
 # the VMR synchronization step is run to validate that the PR can be merged and later
 # synchronized into the VMR without problems.
 # You can do this by allowing the Synchronize_VMR stage from above in PRs.
-- ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
-  - template: eng/pipelines/templates/stages/vmr-build.yml
-    parameters:
-      vmrBranch: ${{ parameters.vmrBranch }}
-      isBuiltFromVmr: false
+# - ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
+#   - template: eng/pipelines/templates/stages/vmr-build.yml
+#     parameters:
+#       vmrBranch: ${{ parameters.vmrBranch }}
+#       isBuiltFromVmr: false
 
 - ${{ if and(ne(variables['System.TeamProject'], 'public'), notin(variables['Build.Reason'], 'PullRequest')) }}:
   - stage: Publish