Remove unused mariadb PVC from ironclad

MariaDB has been moved to external Incus containers, PVC is no longer needed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

k8s/ironclad/pvc-mariadb.yaml

@@ -1,11 +0,0 @@
-apiVersion: v1
-kind: PersistentVolumeClaim
-metadata:
-  name: mariadb-pvc
-spec:
-  accessModes:
-  - ReadWriteOnce
-  storageClassName: longhorn
-  resources:
-    requests:
-      storage: 5Gi