ci: Make expedite pipelines way faster by running less jobs

What does this MR do and why?

Given the following, I think pipeline:expedite pipelines should be way faster:

• only master:broken MR are allowed to have pipeline:expedite, which means master is already broken and the priority is to fix it
• in most cases, pipeline:expedite MRs are reverts of MRs that were merged a few hours earlier, so the risk of breaking master even more with the revert is minimal compared to keeping master broken while pipeline:expedite pipeline is running
• the merge commit will trigger a complete pipeline anyway afterward, so in the worst case, master will stay broken after merge 🤷🏼

This MR implements this proposal by only running lint jobs, assets compilation and rspec fail-fast jobs.

Screenshots or screen recordings

MR acceptance checklist

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

Related to #407376 (closed)