Make testScalarFunctions directly executable in test runners.

[pj-spoelders]

Currently you need to run the whole encompassing ScalarFunctionsTestBase derived test class to also run the nested WithAutomaticParameterDiscovery class and its very convoluted testScalarFunctions test from test runner UIs (tried intellij's and eclipse's).
The nested class and its method do not show up there. Probably because these are part of the abstract ScalarFunctionsTestBase class, which is an abstract class (as this test framework was designed).

This could be improved.

As a bonus: the current testScalarFunctions test uses a caching system which is overly complex. It should be seen if this can somehow be improved. Probably not a simple task as it depends on trying out various combinations and then caching those that DO work on the Exasol database to retry later to speed up things.

[pj-spoelders]

The bigger problem here is this nested class has a different junit test lifecycle: @TestInstance(PER_CLASS)
This makes fixing this issue hard without breaking existing implementations.
When we remove the nested class as scope and change the encompassing junit test lifecycle the existing static beforeAll and afterAll defined in derived classes are not called. This is a breaking change. However I think it beats other alternatives which will require more intensive refactoring and also will result in breakage.

[pj-spoelders]

Solved in the following way:

• The nested class is now removed.
• The setup and teardown of the required infrastructure in the derived classes now needs to be moved to the abstract beforeAllSetup and afterAllTeardown methods that need to be implemented.
• This is a breaking change.