Grafana 9.3.1 version rollbacked my legacy alert rule configurations

Question

I have recently upgraded my grafana image(helm chart) version 8.2.7 -> 9.3.1, After upgrade I noticed my existing alerts rules are missing

According to my analysis new version replaced the legacy alert configuration, So rollback the legacy alerting I tried following configuration in grafana.ini, but still my alert rules are missing

grafana.ini:
  alerting: 
    enabled: true
  unified_alerting
    enabled: false

Reference

https://grafana.com/docs/grafana-cloud/alerting/migrating-alerts/roll-back/

https://github.com/grafana/helm-charts/issues/1464

Could anyone please advise me on this