test: change summary job to only run on failure

This saves time when jobs are successful, as we don't need to wait for
GitHub to spin up a new VM.

.github/workflows/test.yml

@@ -85,14 +85,11 @@ jobs:
   success:
     name: All action tests passed
     needs: [check]
-    if: always()
+    if: cancelled() || failure()
     runs-on: ubuntu-latest
 
     steps:
       - name: Raise failure
-        if: |
-          contains(needs.*.result, 'failure') ||
-          contains(needs.*.result, 'cancelled')
         run: |
           echo "::error::There are failing required jobs"
           exit 1