Address unresolved comments from Object Lock changes

[NiaStorj]

Summary:

Address feedback on code reviews for Object Lock

Document:

https://docs.google.com/document/d/1Xk5dd7FVAkz3jyUz6XZ4Zn56jEmtEYPmJZ8HN8MMJ2U/edit

### Tasks
- [x] https://review.dev.storj.io/c/storj/storj/+/13759
- [x] https://review.dev.storj.io/c/storj/storj/+/13871
- [x] https://review.dev.storj.io/c/storj/storj/+/13872
- [ ] https://review.dev.storj.io/c/storj/storj/+/13876
- [ ] https://review.dev.storj.io/c/storj/storj/+/13890
- [ ] https://review.dev.storj.io/c/storj/storj/+/13878
- [ ] https://review.dev.storj.io/c/storj/storj/+/13880
- [x] https://review.dev.storj.io/c/storj/storj/+/13877

[storj-gerrit[bot]]

Change satellite/metabase: fix SetObjectRetention race condition mentions this issue.

[storj-gerrit[bot]]

Change satellite/metainfo: refactor simple validation of request fields mentions this issue.

[storj-gerrit[bot]]

Change satellite/metabase: fix data race when deleting locked objects mentions this issue.