Restore CI

Author: anuraaga

.github/workflows/contrib.yml

@@ -19,5 +19,8 @@ jobs:
     uses: open-telemetry/opentelemetry-python-contrib/.github/workflows/core_contrib_test_0.yml@main
     with:
       CORE_REPO_SHA: ${{ github.sha }}
-      # DO NOT SUBMIT: Testing https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4165
-      CONTRIB_REPO_SHA: d6b916049d9c1c7a3664a15a5cfbef722265dbd0
+      CONTRIB_REPO_SHA: ${{ github.event_name == 'pull_request' && (
+          contains(github.event.pull_request.labels.*.name, 'prepare-release') && github.event.pull_request.head.ref ||
+          contains(github.event.pull_request.labels.*.name, 'backport') && github.event.pull_request.base.ref ||
+          'main'
+        ) || 'main' }}