chore: make result job fail when any previous job fails (#9455) (CP: 25.2) (#9472)

This PR cherry-picks changes from the original PR #9455 to branch 25.2.
---
#### Original PR description
> The results job only failed on test failures captured in report XMLs.
It did not fail when any previous job failed, for example the build, or
when a test job runs into an error that didn't produce failed tests.
> 
> This changes the result step to run unconditionally and fail on any
job's failure/canceled result, so it can serve as the single required
check. Renamed the job to "Validation result" to reflect the broader
responsibility.
> 
> This change was triggered by the discussion in this PR:
#9448. There the required
checks on "Unit tests", "Package WAR", etc. prevented the PR from
merging, as with `[skip ci]` those jobs are never actually run due to
`fast-tests` being skipped and never spawning them. As such it seems
useful to have a single result job as required check that reports
success for all previous jobs and test results.

Co-authored-by: Sascha Ißbrücker <sissbruecker@vaadin.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

.github/workflows/validation.yml

@@ -498,9 +498,9 @@ jobs:
           if-no-files-found: ignore
 
   results:
-    name: Collect tests
+    name: Validation result
     needs: [build, fast-tests, its]
-    if: always() && needs.build.result == 'success'
+    if: always()
     runs-on: ubuntu-latest
     permissions:
       contents: read
@@ -668,10 +668,16 @@ jobs:
               gh api -X DELETE "repos/$GH_REPO/actions/artifacts/$id" || true
             done
 
-      - name: Fail if any test failed
+      - name: Fail if any job or test failed
         if: always()
         run: |
           failed=false
+          # Job-level failures (build/setup/compile/packaging/infra).
+          # Skipped is OK: skip-ci skips fast-tests/its, empty builds skip its.
+          for r in "${{ needs.build.result }}" "${{ needs.fast-tests.result }}" "${{ needs.its.result }}"; do
+            [[ "$r" == "failure" || "$r" == "cancelled" ]] && failed=true
+          done
+          # Actual test failures captured in the published reports.
           [[ "${{ steps.unit-dorny.outputs.conclusion }}" == "failure" ]] && failed=true
           [[ "${{ steps.wtr-dorny.outputs.conclusion }}"  == "failure" ]] && failed=true
           [[ "${{ steps.it-dorny.outputs.conclusion }}"   == "failure" ]] && failed=true