chore(helmchart): Remove db-migrations from mlp chart; migrations now run at app start up

[maniteja6799]

Motivation

Remove the Kube manifests and configurations related to db-migrations from the mlp chart. Since starting mlp:1.7.1 DB-migrations are running at app start up

Changes

• Removed configMap loading db-migrations
• remove init containers in mlp-deployment which run db-migrations
• remove volume mounts for configMap wherever used.
• Increment chart version
• update mlp image tag to 1.7.2

[romanwozniak]

Please also remove [db-migrations](https://github.com/gojek/mlp/blob/main/charts/mlp/db-migrations) symlink