Fix: transition to math/rand/v2 for Improved Performance and Code Clarity

[Aoang]

Description

This Pull Request removes a reference to runtime.fastrand in go/hack/runtime.go and replaces a call to hack.FastRand() with math/rand/v2.Uint32N in go/pools/smartconnpool/pool.go. These change aim to enhance code readability, performance, and reduce dependency on specific runtime implementations.

math/rand/v2 employs Lemire's algorithm in functions such as N, IntN, UintN, and others. Preliminary benchmark tests show a 40% improvement compared to Int31n in v1 and a 75% improvement compared to Int63n in v1.

Furthermore, math/rand/v2 default utilizes ChaCha8 for the global random number generator in each OS thread.

Related Issue(s)

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.65%. Comparing base (fbaed97) to head (1e0aa22).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15438      +/-   ##
==========================================
+ Coverage   65.63%   65.65%   +0.01%     
==========================================
  Files        1562     1563       +1     
  Lines      194249   194379     +130     
==========================================
+ Hits       127502   127618     +116     
- Misses      66747    66761      +14     

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[dbussink]

I don't think we should keep using this hack, but switch to https://pkg.go.dev/math/rand/v2#Uint32N from the only place where we use this, namely in go/pools/smartconnpool/pool.go.

[Aoang]

I don't think we should keep using this hack, but switch to https://pkg.go.dev/math/rand/v2#Uint32N from the only place where we use this, namely in go/pools/smartconnpool/pool.go.

Should go/hack be cleaned up?

[dbussink]

Should go/hack be cleaned up?

Yes, we can then clean up runtime.fastrand.

[dbussink]

You'll also need to fix the DCO check.

[dbussink]

@Aoang Can you update the PR description as well with how the new approach works?

[dbussink]

@vmg Wanna also take a look here?