Fix test_volume_backup_restore test

The test_volume_backup_restore test was failing with 403 Forbidden when
Cinder backup attempted to create the volumebackups container in Swift.

Root cause: The tempest-tests workflow step 2 (scenario-tests) was
missing the auth.tempest_roles override. Test users created during
scenario tests only received member and reader roles, not swiftoperator,
which is required to create Swift containers.

Assisted-By: Claude Code/claude-4.5-sonnet
Signed-off-by: Harald Jensås <hjensas@redhat.com>

Author: hjensas

scenarios/3-nodes/test-operator/tempest-tests.yml

@@ -118,6 +118,8 @@ spec:
           memory: 6Gi
       tempestconfRun:
         create: false
+        overrides: |
+          auth.tempest_roles swiftoperator
       tempestRun:
         concurrency: 2
         includeList: |