Investigate what we can defer loading after LCP in the Repository page

Proposal

Look at the waterfall of the Sitespeed results for the Repository Large page and identify what we can work on to make LCP trigger earlier or at least perform consistently below 2.5s

Note: Pre-loading things on StartupJS has already been done.

Might be useful looking at places where we can shave off bytes from the bundles for this page.

See dashboard: https://dashboards.gitlab.net/d/000000043/sitespeed-page-summary?from=now-30d&orgId=1&to=now&var-base=sitespeed_io&var-path=desktop&var-group=gitlab_com&var-page=SourceCode_Repo_Large&var-browser=chrome&var-connectivity=cable&var-function=median