Turning off auto-update needs hitting update

[OrfeasLitos]

Problematic scenario:

• Auto-update has been left on at the time of submission.
• We want to push a change to the original repo after submission, but we don't want the "last change" timestamp as shown in the anonymous repo to change.
• Alice owns the original repo, Bob owns the anonymous repo.
• Alice makes the change to the repo, says it to Bob, and goes to sleep (so there is no way to quickly remove the pushed change, as Bob doesn't have access).
• Bob realizes that auto-update will kick in soon and rushes to turn off auto-update. In the process, he has to hit "Update", which deactivates auto-update but also forces an update of the anonymous repo, picking up Alice's change. The timestamp is now after the submission deadline.
• A reviewer sees the timestamp and marks the paper as desk reject.

Proposed solution:
Either change the "auto-update" on the server when the tickbox is toggled, or add an "Apply changes" button that is separate from the "update" button.