Reduce queries on group search API for blobs scope [RUN ALL RSPEC] [RUN AS-IF-FOSS]

What does this MR do?

Related to #326754 (closed)

Add preloading for blobs, this should help with group searches in blobs scope for the search API. On GitLab.com the global scope does not support code searches, but this could help self managed if they have Advanced Search enabled for global search.

The preload methods have already been setup for blobs on the web searches in: !57826 (merged). This MR adds the same capabilities in the API side (and adds a few specs).

The preloading for the blob's project data is done in ee/lib/elastic/latest/git_class_proxy.rb

Screenshots (strongly suggested)

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