backport: upgrade golang to latest patch of go 1.21 in release/3.1.x

[randmonkey]

What this PR does / why we need it:

Upgrade golang version to 1.21.9 in release/3.1.x branch.

Which issue this PR fixes:

Special notes for your reviewer:

The intention of this PR is to update ALL appearances of golang version to 1.21 to use the latest patch of golang 1.21. But when I run go mod tidy locally, it added toolchain go1.22.2 which is my local golang version. (Is it affected by local config of golang?)
So I updated it to 1.21.9.

PR Readiness Checklist:

Complete these before marking the PR as ready to review:

• the CHANGELOG.md release notes have been updated to reflect any significant (and particularly user-facing) changes introduced by this PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

❗ No coverage uploaded for pull request base (release/3.1.x@e101c1d). Click here to learn what that means.

❗ Current head 3d30654 differs from pull request most recent head 503607c. Consider uploading reports for the commit 503607c to get more accurate results

Additional details and impacted files

@@               Coverage Diff               @@
##             release/3.1.x   #5905   +/-   ##
===============================================
  Coverage                 ?   71.9%           
===============================================
  Files                    ?     176           
  Lines                    ?   18312           
  Branches                 ?       0           
===============================================
  Hits                     ?   13184           
  Misses                   ?    4163           
  Partials                 ?     965           

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