Trim prerenders

[damianhxy]

Description

• Remove prerender for version links
• Remove prerender for previous student

Motivation and Context

In #1415 and #1503, prerender was used with the goal of loading likely pages in advance to reduce loading times.

However, through testing, it turns out that only one link (previous student) was prerendered (actually NoState Prefetch). Given that TAs are most likely to go to the next student, this PR removes all prerenders except for the link to the next student.

How Has This Been Tested?

1. Use Chrome incognito
2. Start logging with chrome://net-export/
3. Load a page with prev / next version / student available and wait for a few seconds
4. Stop logging
5. Import log file to netlog viewer

Before changes: Only previous student prerendered (1908). Previous version (1906), next version (1910), next student (1895) links encounter a Rate Limit Exceeded.

After changes: Next student prerendered (1895).

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have run rubocop for style check. If you haven't, run overcommit --install && overcommit --sign to use pre-commit hook for linting
• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, included in this PR

[victorhuangwq]

I have only one comment. But in general it seems to be as intended