refactor: replace experimental maps and slices with stdlib

[Juneezee]

Summary

Follow-up of #6169 (comment).

The experimental functions are now part of the standard library as of Go 1.21 and Go 1.23.

The key difference is that maps.Keys and maps.Values in the golang.org/x/exp package return a slice, whereas maps.Keys and maps.Values in the standard library return an iterator. To work with slices, we need to use slices.Collect to convert the iterator into a slice.

Reference: https://go.dev/doc/go1.21#slices
Reference: https://go.dev/doc/go1.23#new-unique-package

Test Plan

Go compiler

[jannotti]

Just one small change, to avoid having a variable called result which is not the result for the function.

Thanks for doing this!

[gmalouf]

Thank you!

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 8 lines in your changes missing coverage. Please review.

Project coverage is 51.87%. Comparing base (0bc3d7e) to head (4742e34).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
daemon/algod/api/server/v2/utils.go	0.00%	6 Missing ⚠️
cmd/algokey/keyreg.go	0.00%	1 Missing ⚠️
netdeploy/network.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6179      +/-   ##
==========================================
+ Coverage   51.86%   51.87%   +0.01%     
==========================================
  Files         639      639              
  Lines       85492    85489       -3     
==========================================
+ Hits        44344    44351       +7     
+ Misses      38331    38324       -7     
+ Partials     2817     2814       -3     

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