fix(operator): enable processing of historical / missed etcd-backed roster updates

[strieflin]

Fixes: #15

fix(operator): get rid of unsupported trace logging level

fix(operator): use retries to address race condition on etcd roster updates

fix(operator-chart): remove legacy chart folder incl. migration of changelog updates

fix(operator): use numeric user and group ID in operator dockerfile

[codecov]

Codecov Report

Merging #49 (e07bef2) into master (859f0cb) will increase coverage by 0.15%.
The diff coverage is 74.41%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #49      +/-   ##
==========================================
+ Coverage   74.55%   74.71%   +0.15%     
==========================================
  Files           7        7              
  Lines        1077     1135      +58     
==========================================
+ Hits          803      848      +45     
- Misses        198      206       +8     
- Partials       76       81       +5     

Impacted Files	Coverage Δ
...ator/controllers/tuplegenerationtask_controller.go	75.96% <40.00%> (-0.73%)	⬇️
...rator/controllers/tuplegenerationjob_controller.go	68.03% <75.94%> (+0.16%)	⬆️
...lyshko-operator/controllers/scheduling_strategy.go	100.00% <100.00%> (ø)
...controllers/tuplegenerationscheduler_controller.go	66.39% <100.00%> (ø)

... and 1 file with indirect coverage changes

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[sbckr]

LGTM