Consolidate all the code checkers into one job

[MorrisJobke]

• moves all the small checks that basically only that a few seconds into one job
• removes overhead of cloning it 6 times

[mention-bot]

@MorrisJobke, thanks for your PR! By analyzing the history of the files in this pull request, we identified @LukasReschke, @rullzer and @danxuliu to be potential reviewers.

[codecov]

Codecov Report

Merging #4669 into master will decrease coverage by <.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #4669      +/-   ##
============================================
- Coverage     54.29%   54.29%   -0.01%     
  Complexity    22093    22093              
============================================
  Files          1360     1360              
  Lines         84686    84686              
  Branches       1325     1325              
============================================
- Hits          45980    45979       -1     
- Misses        38706    38707       +1

Impacted Files	Coverage Δ	Complexity Δ
lib/private/Files/Cache/Propagator.php	94.93% <0%> (-1.27%)	16% <0%> (ø)
lib/private/Security/CertificateManager.php	92.78% <0%> (-1.04%)	38% <0%> (ø)
lib/private/Server.php	93.51% <0%> (+0.14%)	120% <0%> (ø)	⬇️

[rullzer]

Makes sense

[MorrisJobke]

CI only -> merge