Build/Test Tools: Don’t send a Slack notice for a workflow’s first failure.

After [53947], all workflows will automatically be restarted once in an attempt to rule out reasons for failures, such as timeouts or network hiccups.

Second attempt at [56404], which was previously reverted in [56407].
See #58867.

git-svn-id: https://develop.svn.wordpress.org/trunk@56780 602fd350-edb4-49c9-b593-d223f7449a82

.github/workflows/slack-notifications.yml

@@ -71,6 +71,10 @@ jobs:
               run_id: ${{ github.run_id }},
             });
 
+            if ( '${{ inputs.calling_status }}' == 'failure' && workflow_run.data.run_attempt == 1 ) {
+              return 'first-failure';
+            }
+
             // When a workflow has been restarted to fix a failure, check the previous run attempt.
             if ( workflow_run.data.run_attempt > 1 ) {
               const previous_run = await github.rest.actions.getWorkflowRunAttempt({
@@ -157,7 +161,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 5
     needs: [ prepare ]
-    if: ${{ inputs.calling_status == 'failure' || failure() }}
+    if: ${{ needs.prepare.outputs.previous_conclusion != 'first-failure' && inputs.calling_status == 'failure' || failure() }}
 
     steps:
       - name: Post failure notifications to Slack