Add groupId value propagation tests for ZIP publication task

[lukas-vlcek]

Is your feature request related to a problem? Please describe.

We made it possible to configure the ZIP publication groupId value in #4156 (followed by #4360) and this was back-ported to 2.x branch in #4733.

This change requires some configuration changes in couple of existing plugins. In order to make it more obvious how each plugin should be updated we can implement more tests that verify how the groupId value is inherited/propagated in specific cases.

For example what happens when the group value is defined only in the top level allprojects section. Or what happens when its value is defined on several levels.

Describe the solution you'd like

Adding specific tests to PublishTests.java would be helpful. Should there be any changes in how gradle (or any of its plugins involved in the ZIP publications processing) handles the propagation of the value then these tests can help discover it in advance.

Describe alternatives you've considered

There are no alternatives. The process of plugin configuration and release can only benefit from more automated tests (in this case we can think of the test code as a "living" documentation).

Additional context

There was a discussion on the original PR that led to the idea of adding more tests: #4733 (comment)