Geo: Resolve sticky failures when attachments are missing on primary

What does this MR do?

Caps the Geo file download failure retry_at time to 7 days later.

What are the relevant issue numbers?

Resolves gitlab-com/migration#458 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• EE specific content should be in the top level /ee folder
• For a paid feature, have we considered GitLab.com plans, how it works for groups, and is there a design for promoting it to users who aren't on the correct plan?