Use builtin min and max functions

[jhalterman]

With the upgrade to Go 1.21 (#7282), grpc-go can use the new builtin min and max functions. This commit removes existing functions and uses the built-ins instead.

RELEASE NOTES: none

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: jhalterman / name: Jonathan Halterman (6933fc8, 1e146b1)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.44%. Comparing base (e524655) to head (1e146b1).
Report is 30 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7478      +/-   ##
==========================================
+ Coverage   81.40%   81.44%   +0.04%     
==========================================
  Files         357      357              
  Lines       27243    27233      -10     
==========================================
+ Hits        22176    22180       +4     
+ Misses       3850     3833      -17     
- Partials     1217     1220       +3     

Files	Coverage Δ
balancer/rls/internal/adaptive/lookback.go	100.00% <ø> (ø)
credentials/alts/internal/conn/record.go	84.69% <ø> (-0.61%)	⬇️
internal/channelz/channelmap.go	89.89% <ø> (-0.21%)	⬇️
internal/transport/controlbuf.go	89.82% <ø> (+0.34%)	⬆️
internal/transport/http2_client.go	91.82% <100.00%> (-0.43%)	⬇️
internal/transport/http2_server.go	91.10% <100.00%> (ø)
xds/internal/balancer/outlierdetection/balancer.go	88.58% <ø> (+0.24%)	⬆️

... and 17 files with indirect coverage changes

[purnesh42H]

lgtm. Thanks for the contribution!

[arvindbr8]

LGTM, do you mind reverting the unrelated changes please?