chore: get rid of golang.org/x/exp/{constraints,slices} modules

[zjx20]

Since Go 1.21, these modules were moved into the standard library. However, we can't remove golang.org/x/exp/maps yet, as the standard library doesn't provide the Keys() and Values() methods.

ref links:

• https://go.dev/blog/go1.21
• maps: remove Keys and Values for Go 1.21 golang/go#61538

[codecov]

Codecov Report

Attention: Patch coverage is 20.00000% with 8 lines in your changes missing coverage. Please review.

Project coverage is 61.30%. Comparing base (c65ed8c) to head (1eb7572).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ntrollers/apps/configuration/reconfigure_policy.go	0.00%	3 Missing ⚠️
...ollers/dataprotection/log_collection_controller.go	0.00%	2 Missing ⚠️
controllers/extensions/addon_controller_stages.go	0.00%	1 Missing and 1 partial ⚠️
...llers/apps/configuration/rolling_upgrade_policy.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8239      +/-   ##
==========================================
- Coverage   61.36%   61.30%   -0.06%     
==========================================
  Files         349      349              
  Lines       40290    40280      -10     
==========================================
- Hits        24722    24692      -30     
- Misses      13338    13355      +17     
- Partials     2230     2233       +3     

Flag	Coverage Δ
unittests	61.30% <20.00%> (-0.06%)	⬇️

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