Fix KvmSshToAgentEnabled setting description and make it dynamic

[nvazquez]

Description

This PR makes the setting kvm.ssh.to.agent dynamic, and updates its description as pointed out on the issue #12529.

The setting has been introduced with the wrong description on the PR: #3239

Fixes: #12529

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)
• Build/CI
• Test (unit or integration test code)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

How did you try to break this feature and the system with this change?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 3.57%. Comparing base (5aced73) to head (ba979fa).

❗ There is a different number of reports uploaded between BASE (5aced73) and HEAD (ba979fa). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (5aced73)	HEAD (ba979fa)
unittests	1	0

Additional details and impacted files

@@              Coverage Diff              @@
##               main   #12533       +/-   ##
=============================================
- Coverage     17.85%    3.57%   -14.28%     
=============================================
  Files          5930      448     -5482     
  Lines        531409    37908   -493501     
  Branches      64963     7008    -57955     
=============================================
- Hits          94869     1357    -93512     
+ Misses       425914    36385   -389529     
+ Partials      10626      166    -10460     

Flag	Coverage Δ
uitests	3.57% <ø> (ø)
unittests	?

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[nvazquez]

@blueorangutan package

[blueorangutan]

@nvazquez a [SL] Jenkins job has been kicked to build packages. It will be bundled with no SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✖️ el8 ✖️ el9 ✖️ debian ✖️ suse15. SL-JID 16570

[shwstppr]

@nvazquez should we target this for 4.22.1 or 4.20.3 as the config is present there?