mgr/smb: Replace "clusters" with "shares" in error status

In the following error response the list of active shares is incorrectly
displayed with "clusters" field.
{
  "resource": {
    "resource_type": "ceph.smb.cluster",
    "cluster_id": "smbcluster",
    "intent": "removed"
  },
  "clusters": [
    "smbshare"
  ],
  "msg": "cluster in use by shares",
  "success": false
}

Replace "clusters" with "shares" to avoid confusion.

Signed-off-by: Anoop C S <[email protected]>

Author: anoopcs9

src/pybind/mgr/smb/handler.py

@@ -758,7 +758,7 @@ def _check_cluster(cluster: ClusterRef, staging: _Staging) -> None:
                 cluster,
                 msg="cluster in use by shares",
                 status={
-                    'clusters': [
+                    'shares': [
                         shid
                         for cid, shid in share_ids
                         if cid == cluster.cluster_id