fix(lint): Update golangci-lint to v2

[thunderboltsid]

migrate golangci-lint config using built-in migrate tooling.

[adiantum]

approve tests

[codecov]

Codecov Report

Attention: Patch coverage is 30.76923% with 18 lines in your changes missing coverage. Please review.

Project coverage is 44.00%. Comparing base (883f3c9) to head (812d146).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
controllers/nutanixmachine_controller.go	23.52%	13 Missing ⚠️
controllers/nutanixcluster_controller.go	40.00%	3 Missing ⚠️
controllers/helpers.go	50.00%	2 Missing ⚠️

❌ Your patch check has failed because the patch coverage (30.76%) is below the target coverage (75.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #514      +/-   ##
==========================================
+ Coverage   43.96%   44.00%   +0.03%     
==========================================
  Files          18       18              
  Lines        2593     2593              
==========================================
+ Hits         1140     1141       +1     
- Misses       1417     1418       +1     
+ Partials       36       34       -2     

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