Create a smaller cache for coverage jobs

From Draft to Ready

• All discussions are resolved

Context

Closes #421190 (closed)

What does this MR do and why?

Configure a smaller cache for coverage jobs

For now, this cache will only be used by the rspec:coverage job, but it probably will be expanded to the other jobs extending .coverage-base.

This is done for performance purposes: downloading the cache takes 12 seconds, and we declare 4 gems out of the 70+ that are installed.

Does it work?

Thanks to this test commit, I pushed a cache from this MR:

• The job updating the ruby gems coverage cache was successful ✅
• The rspec:coverage job used this cache ✅

Performance

We are saving between 14s and 17s 🚀

• 2s to download the new cache (instead of ~12-15s)
• 2s for the bundle install (instead of ~6s)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.