Enable basic molecule tests for agent role

[robin-checkmk]

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes
• Other (please describe):

What is the current behavior?

There are no molecule tests for the agent role.

What is the new behavior?

Very basic tests have been implemented. Currently, only the installation itself is verified, but that will be extended in the future.

Other information

[robin-checkmk]

The molecule tests fail at all Python versions other than 3.8. However, server molecule tests run just fine and they are literally the same. I smell a flake here, so will let this cook for some days. Maybe it resolves on its own.

Hints are very welcome, if you spot a problem. 👀

[robin-checkmk]

Apparently there is several things broken with molecule and its dependencies. I will give the project some more time before I give it another shot.

References:

• 'pip install molecule-plugins[docker]' does not work as expected ansible-community/molecule-plugins#135
• Remove lint command ansible/molecule#3802
• urllib3 v2 incompatibility docker/docker-py#3113
• molecule broken with latest version of ansible-compat ansible/molecule#3903

[robin-checkmk]

With molecule 5.0.1 the issues mentioned above seem fixed, or at least operational.
I removed the -lint scenario - also for the server role - as that is obsolete starting with molecule 5.0.0.

With these changes, the PR is ripe to be merged.