Build/Test Tools: Re-add Slack notices for E2E workflow.

This re-adds Slack notices for the E2E workflow in the 5.9 branch.

These were mistakenly removed in [58358].

See #61733, #61213.

git-svn-id: https://develop.svn.wordpress.org/branches/5.9@58794 602fd350-edb4-49c9-b593-d223f7449a82

.github/workflows/end-to-end-tests.yml

@@ -50,6 +50,22 @@ jobs:
       php-version: '8.0'
       install-gutenberg: false
 
+  slack-notifications:
+    name: Slack Notifications
+    uses: WordPress/wordpress-develop/.github/workflows/slack-notifications.yml@trunk
+    permissions:
+      actions: read
+      contents: read
+    needs: [ e2e-tests ]
+    if: ${{ github.repository == 'WordPress/wordpress-develop' && github.event_name != 'pull_request' && always() }}
+    with:
+      calling_status: ${{ contains( needs.*.result, 'cancelled' ) && 'cancelled' || contains( needs.*.result, 'failure' ) && 'failure' || 'success' }}
+    secrets:
+      SLACK_GHA_SUCCESS_WEBHOOK: ${{ secrets.SLACK_GHA_SUCCESS_WEBHOOK }}
+      SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
+      SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
+      SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
+
   failed-workflow:
     name: Failed workflow tasks
     runs-on: ubuntu-latest