CI: Comment to look up Flaky test tracker on e2e test failure

.github/workflows/call-e2e-test.yml

@@ -66,3 +66,9 @@ jobs:
           name: Test Results ${{ inputs.os }}-${{ inputs.browser }}-${{ inputs.editor-mode }}-${{ inputs.events-mode }}-${{ inputs.prod && 'prod' || 'dev' }}-${{ inputs.node-version }}-${{ inputs.override-react-version }}
           path: ${{ env.test_results_path }}
           retention-days: 7
+      - name: Flaky test notice PR comment
+        if: failure()
+        uses: thollander/actions-comment-pull-request@v2
+        with:
+          message: |
+            E2E tests failed on [this run](https://github.com/facebook/lexical/actions/runs/${{ github.run_id }}). Please check if the failure is due to a flaky test. Visit the [Flaky Test Tracker](https://github.com/facebook/lexical/discussions/6289) for known flaky tests, and record the failed test run there if its a flaky failure.