Fix prune deleted volumes for clones

During prune deleted volumes option, if volume is offline, manila calls
for ONTAP volume-destroy API. However if volume has one or more clones,
the destroy operation fails. So upon receving clone related error, check
clone spilt status and if not started, start it.

manila/share/drivers/netapp/dataontap/client/client_cmode.py

@@ -3963,9 +3963,14 @@ def prune_deleted_volumes(self):
                 try:
                     client.send_request(
                         'volume-destroy', {'name': volume_name})
-                except netapp_api.NaApiError:
+                except netapp_api.NaApiError as e:
                     LOG.error(
                         'Pruning soft-deleted volume %s failed', volume_name)
+                    if e.code == netapp_api.EVOLDEL_NOT_ALLOW_BY_CLONE:
+                        if self.volume_clone_split_status(volume_name) != 100:
+                            self.volume_clone_split_start(volume_name)
+                            LOG.debug('Starting clone split for '
+                                      'volume %s ', volume_name)
 
     @na_utils.trace
     def create_snapshot(self, volume_name, snapshot_name):