PMM-14829 Remove crypto package fork usage.

[JiriCtvrtka]

PMM-14829

FB: Percona-Lab/pmm-submodules#4257

This PR removes the project’s dependency on the Percona-Lab fork of golang.org/x/crypto and adjusts the local bcrypt implementation so the codebase can use the upstream golang.org/x/crypto/bcrypt module.

Most of the code was copied from golang.org/x/crypto/bcrypt. I made edits to satisfy linters. The functions GenerateFromPasswordAndSalt and newFromPasswordAndSalt are ours.

[codecov]

Codecov Report

❌ Patch coverage is 79.54545% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 47.76%. Comparing base (46df6bf) to head (43f9ac9).
⚠️ Report is 1 commits behind head on v3.

Files with missing lines	Patch %	Lines
managed/utils/crypto/bcrypt/bcrypt.go	79.54%	9 Missing and 9 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##               v3    #5115      +/-   ##
==========================================
+ Coverage   47.69%   47.76%   +0.06%     
==========================================
  Files         409      410       +1     
  Lines       41881    41969      +88     
==========================================
+ Hits        19977    20047      +70     
- Misses      19936    19945       +9     
- Partials     1968     1977       +9     

Flag	Coverage Δ
admin	35.80% <ø> (ø)
agent	53.23% <ø> (ø)
managed	47.71% <79.54%> (+0.10%)	⬆️
vmproxy	72.09% <ø> (ø)

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