build: fail gha-done check when required job fails (#51067)

fix: fail gha-done when any required job failed

Previously, the `gha-done` gate job used an `if:` expression that
evaluated to false whenever any needed job reported a failure, which
caused the job to be *skipped* rather than *failed*. GitHub branch
protection treats skipped required checks as non-blocking, so a PR
could be marked mergeable even though one of its test jobs had failed.

Keep the job always running and move the failure check into a step
that explicitly exits 1 when any dependency failed or was cancelled,
so the "GitHub Actions Completed" required check actually blocks the
merge in that case.

Notes: none

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Samuel Attard <samuel.r.attard@gmail.com>

.github/workflows/build.yml

@@ -441,8 +441,11 @@ jobs:
     permissions:
       contents: read
     needs: [docs-only, macos-x64, macos-arm64, linux-x64, linux-x64-asan, linux-arm, linux-arm64, windows-x64, windows-x86, windows-arm64]
-    if: always() && github.repository == 'electron/electron' && !contains(needs.*.result, 'failure')
+    if: always() && github.repository == 'electron/electron'
     steps:
+    - name: Fail if any needed job failed or was cancelled
+      if: contains(needs.*.result, 'failure') || contains(needs.*.result, 'cancelled')
+      run: exit 1
     - name: GitHub Actions Jobs Done
       run: |
         echo "All GitHub Actions Jobs are done"