feat: k6 perf example

[tkonieczny]

• k6 test
• example workflows
  • k6-perf-test (artifacts)
  • k6-perf-test-workers (workers + artifacts)
  • k6-perf-test-workers-prometheus (workers + artifacts + prometheus with native-histograms enabled
• prometheus+grafana values files

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 19.65%. Comparing base (69dcd7f) to head (38b82f3).
Report is 2272 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6039      +/-   ##
==========================================
- Coverage   25.80%   19.65%   -6.16%     
==========================================
  Files         198      576     +378     
  Lines       15240    57185   +41945     
==========================================
+ Hits         3933    11240    +7307     
- Misses      10917    44953   +34036     
- Partials      390      992     +602     

Flag	Coverage Δ
integrationtests	?
unittests	19.65% <ø> (-0.82%)	⬇️

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