GC objects in metadata chain based on height (epoch)

Is your feature request related to a problem? Please describe.

We need to GC LOCK, TS, and REGULAR objects with expiration set. neo-go has a GC mechanism that is run every block approval; this should be reused, it should not be a separate chain call.

Describe the solution you'd like

1. Extend indices with expiration epoch (if any) from https://github.com/nspcc-dev/neofs-node/pull/3759
2. Adapt neo-go's expiration mechanism and drop object metadata based on this index (likely in batches, not more than N records in DB)

Describe alternatives you've considered

Separate routine triggered externally.

Additional context

https://github.com/nspcc-dev/neofs-node/pull/3759#discussion_r2774809683, smth should GC objects anyway.