GHA: test slack build failed message

.github/workflows/snapshot-eclipse-ls-extensions-build.yml

@@ -6,9 +6,9 @@ concurrency:
 
 on:
   workflow_dispatch:
-  push:
-    branches:
-      - 'main'
+#  push:
+#    branches:
+#      - 'main'
 
 jobs:
   eclipse-ls-extensions:

.github/workflows/test-slack-message.yml

@@ -27,3 +27,11 @@ jobs:
                 }
               ]
             }
+
+  notify-failure:
+    needs: [ slack-message ]
+    uses: ./.github/workflows/notify-failed-build.yml
+    with:
+      link: '[${{ github.run_id }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }})'
+      label: 'Test Build Failed Message'
+    secrets: inherit