Update name of secret that contains Restic credentials

Recent versions of velero changed the name from velero-restic-credentials to the more generic velero-backup-credentials (because velero now supports both restic & kopia).

for https://gitlab.cern.ch/paas-tools/okd4-install/-/merge_requests/1535

tekton-task-templates/restore_pv_job.yaml

@@ -17,7 +17,7 @@ spec:
       volumes:
         - name: velero-restic-credentials
           secret:
-            secretName: velero-restic-credentials
+            secretName: velero-repo-credentials
             defaultMode: 420
         - name: cache
           emptyDir: {}