velero: name the release resources "velero" so repo maintenance runs

Velero 1.15 builds kopia repository maintenance jobs from a Deployment
called "velero" in its namespace. Ours was velero-helm, so every
BackupRepository reported 'error to build maintenance job: Deployment.apps
"velero" not found' and the repos on the NAS were never cleaned up, some
not since March 2025. fullnameOverride renames the Deployment, Service,
ServiceAccount and RBAC; the old velero-helm objects get deleted by hand
since this app doesn't prune.

velero/velero-helm.yaml

@@ -11,6 +11,11 @@ spec:
     targetRevision: 8.4.0
     helm:
       values: |
+        # Velero builds its repository maintenance jobs from a Deployment
+        # named "velero". Under the default name (velero-helm) every
+        # maintenance run failed and the kopia repos on the NAS were never
+        # cleaned up.
+        fullnameOverride: velero
         # The CRD upgrade hook pulls docker.io/bitnami/kubectl, which Bitnami
         # has removed, so every sync hangs on it. The CRDs only change with
         # the chart version; turn this back on (with another kubectl image)