Automate k0sctl version setting across test suites

[kke]

Description

Removes the need to make manual changes for k0sctl version bumps. The version is obtained from hack/tool/go.mod which is updated automatically by dependabot. All the other suites that use k0sctl now get their k0sctl version by reading it from hack/tool/go.mod.

The change to docs/nllb.md in previous bumps is omitted here - the version number there is cosmetic.

This should make a dependabot PR like #3906 be enough for bumping the k0sctl dependency.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• Manual test
• Auto test added

Checklist:

• My code follows the style guidelines of this project
• My commit messages are signed-off
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• I have checked my code and corrected any misspellings

[twz123]

We would need to trigger the ostests before merging any automatic version bumps. This might get forgotten if it's not obvious that the go.mod version change in hack/tool changes the k0sctl version in the ostests and network tests. Moreover, I think we have a quite outdated k0sctl version in the release e2e tests. (But maybe that is better addressed by replacing those with a workflow call to the ostests.)