Investigate - Limit `recently.opened` in settings

MR: Pending

Description

In this issue, we're noticing some 500's in QA tests. It looks like we're running into check_5da3b2910b when the QA user is trying to hit settings sync.

An investigation into the data revealed that the QA user has a ridiculously large value saved in {"storage":{"recently.opened":[...]}}.

Does this list grow indefinitely? Can we add an arbitrary limit of 100 entries to it?

Acceptance Criteria

• This'll require some investigation into how VSCode handles this internally. Why doesn't VSCode just work!?!?
• What is this actually used for?
• Why do we store things we may not use?
• Placeholder issue created per https://handbook.gitlab.com/handbook/engineering/development/dev/create/remote-development/#-breaking-down-large-issues
• Implementation plan for the fix

Follow-up Implementation Notes

• Limit is added in the @gitlab/web-ide project or BE of main project for recently.opened in the state
• Limit will naturally be applied to user's exceeding this limit so that the QA user's data will naturally heal.