ci: Ensure tests pass even under high load

[perlpunk]

Workers don't accept jobs if the load is too high.

Issua: https://progress.opensuse.org/issues/165198

[okurz]

I would prefer less duplication. Could be a helper file called from both locations

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.50%. Comparing base (bdea10a) to head (e995891).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5852   +/-   ##
=======================================
  Coverage   98.50%   98.50%           
=======================================
  Files         395      395           
  Lines       38748    38756    +8     
=======================================
+ Hits        38169    38177    +8     
  Misses        579      579           

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