Geo: Automatically heal uploads on secondaries

This is the next step after https://gitlab.com/gitlab-org/gitlab-ee/issues/7257.

Proposal

Keep following the pattern set by project verification. In the secondary upload verification service, mark the registry for resync if needed.

Acceptance criteria

Missing file:

• Manually delete an upload file on a secondary
• Wait
• The file should reappear

Modified file:

• Manually modify an upload file on a secondary (e.g. if it's a .txt file, add a line to it)
• Wait
• The file should match the primary