WIP: Clean up ocpp-tests in everest-core

[Pietfried]

Describe the problem

The definition of this issue is still WIP.

This PR added ocpp integration tests in everest-core. This issues specifies follow-up todos:

• Remove ocpp and everest configs from everest-aux and make use of pytest markers to change the configuration instead
• Generate certificates instead of checking them in
• Investigate and potentially add currently skipped test cases again
• Reduce sleeps in test cases as much as possible (sometimes it is required)
• Reduce modules in EVerest config to the minimum of whats needed to run the tests
• Avoid starting a new EVerest instance/process for every individual test case - make use of proper setup and teardown mechanism for test suites

EVerest Domain

OCPP, OCPP1.6, OCPP2.0.1, Testing

Affected EVerest Module

No response

Describe your solution

No response

Additional context

No response