add cleanup for orphan snapshot policies

Author: Daman Arora

server/src/main/java/com/cloud/storage/snapshot/SnapshotManagerImpl.java

@@ -1890,9 +1890,24 @@ public boolean start() {
                 logger.debug("Failed to delete snapshot in destroying state: {}", snapshotVO);
             }
         }
+        cleanupOrphanSnapshotPolicies();
+
         return true;
     }
 
+    private void cleanupOrphanSnapshotPolicies() {
+        List<SnapshotPolicyVO> policies = _snapshotPolicyDao.listActivePolicies();
+        if (CollectionUtils.isEmpty(policies)) {
+            return;
+        }
+        for (SnapshotPolicyVO policy : policies) {
+            if (_volsDao.findByIdIncludingRemoved(policy.getVolumeId()) == null) {
+                logger.info("Removing orphan snapshot policy {} for non-existent volume {}", policy.getId(), policy.getVolumeId());
+                deletePolicy(policy.getId());
+            }
+        }
+    }
+
     @Override
     public boolean stop() {
         backupSnapshotExecutor.shutdown();