[ML] .ml-notifications-000002 can also be a legacy template that needs deleting

Fixes elastic#80891

Author: droberts195

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/MlInitializationService.java

@@ -65,6 +65,7 @@ public class MlInitializationService implements ClusterStateListener {
         ".ml-meta",
         ".ml-notifications",
         ".ml-notifications-000001",
+        ".ml-notifications-000002",
         ".ml-state",
         ".ml-stats"
     );