Add server and proxy installation checks on rke2

[ilmanzo]

What does this PR change?

Add basic post-install health-check for the RKE2 kubernetes cluster resources.
Network reachability and product functions are done by subsequent existing tests

Added some helper methods to reach k8s objects and fixed remote_node class to make it work also with kubectl managed resources.

Links

Issue(s): https://github.com/SUSE/spacewalk/issues/30010

Changelogs

• No changelog needed

[github-actions]

👋 Hello! Thanks for contributing to our project.
Acceptance tests will take some time (approx. 1h), please be patient ☕

You can see the progress at the end of this page and at https://github.com/uyuni-project/uyuni/pull/11761/checks
Once tests finish, if they fail, you can check 👀 the cucumber report. See the link at the output of the action.
You can also check the artifacts section, which contains the logs at https://github.com/uyuni-project/uyuni/pull/11761/checks.

If you are unsure the failing tests are related to your code, you can check the "reference jobs". These are jobs that run on a scheduled time with code from master. If they fail for the same reason as your build, it means the tests or the infrastructure are broken. If they do not fail, but yours do, it means it is related to your code.

Reference tests:

• https://github.com/uyuni-project/uyuni/actions/workflows/acceptance_tests_secondary_parallel.yml?query=event%3Aschedule

• https://github.com/uyuni-project/uyuni/actions/workflows/acceptance_tests_secondary.yml?query=event%3Aschedule

KNOWN ISSUES

Sometimes the build can fail when pulling new jar files from download.opensuse.org . This is a known limitation. Given this happens rarely, when it does, all you need to do is rerun the test. Sorry for the inconvenience.

For more tips on troubleshooting, see the troubleshooting guide.

Happy hacking!
⚠️ You should not merge if acceptance tests fail to pass. ⚠️