This is effectively a no-op, the `Left err` case can't actually happen.
- removes some unused logic
- refactors the /healthz endpoint to be clearer
- that includes logging the full QErr if checkMetadataHealth fails,
but it actually can't because the existing Postgres implementation
just lifts
PR-URL: https://github.com/hasura/graphql-engine-mono/pull/2849
GitOrigin-RevId: ac8abf51b6d869ad4048419e36012137c86e5abd