Geo: Investigate uploads on GPRD whose files do not exist

There were 7297, which was strange.

I took the first one, and its registry showed a successful sync. When I marked it for retry, and executed FileDownloadService for it, it downloaded the file and marked the registry as synced again. Now the Upload responds with true to exist?.

• 113 uploads were later destroyed - OK
• 32 now have a file - OK
• 1389 are synced and missing on primary - OK
• 5763 have a file on the primary - NOT OK

• How did this happen for these cases?
• What should be done in the code, and/or manually?
  • Verification https://gitlab.com/gitlab-org/gitlab-ee/issues/5591 would catch this, and auto retry would fix it. Is that sufficient?