Update Dockerfiles to Go 1.22 (Go 1.22: 1/3)

[grdryn]

---

JIRA: https://issues.redhat.com/browse/RHOAIENG-16819

Description

The UBI8 go-toolset image that we use for building is already on 1.22,
so I don't think there's any reason to remain bound to 1.21.

Also, upstream Go only support the two most recent minor versions:
currently that means 1.23 and 1.22; 1.21 is no longer receiving any
updates from the Go developers.

How Has This Been Tested?

• Builds fine
• Runs fine

Screenshot or short clip

Merge criteria

• You have read the contributors guide.
• Commit messages are meaningful - have a clear and concise summary and detailed explanation of what was changed and why.
• Pull Request contains a description of the solution, a link to the JIRA issue, and to any dependent or related Pull Request.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1424   +/-   ##
=======================================
  Coverage        ?   25.81%           
=======================================
  Files           ?       68           
  Lines           ?     5550           
  Branches        ?        0           
=======================================
  Hits            ?     1433           
  Misses          ?     3944           
  Partials        ?      173           

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[grdryn]

/cc @zdtsw @VaishnaviHire

[grdryn]

After a discussion today, what was originally in this PR will now be split into 3 PRs.

• This first one will just have the change to the Dockerfiles, since everything should work as expected by just using a newer version of Go to build, even with the older version set as the minimum version in go.mod
• The second PR will just update the go.mod, but will not fix linter errors (will just silence those that prevent the build from working)
• The third PR will address the linter warnings/errors

[ykaliuta]

probably, README.md should be updated as well for consistency

[grdryn]

@ykaliuta I don't think this change is where the README should be updated, since this change doesn't require 1.22 as a prerequisite for development. I've instead updated the README as part of #1439, since that's where it becomes necessary.

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