added pre-install annotation for db creation migration

Author: akshatsinha007

charts/devtron/templates/migrator.yaml

@@ -455,6 +455,8 @@ kind: Job
 metadata:
   namespace: devtroncd
   name: postgresql-create-databases-{{ randAlphaNum 5 | lower }}
+  annotations:
+    "helm.sh/hook": pre-install
 spec:
   activeDeadlineSeconds: 1500
   ttlSecondsAfterFinished: 1000