Clean up of test cases for BPMN2 processes supported by runtime engine. Currently there are:

• main one SimpleBPMN2ProcessTest that is mixing test with persistence and without it
• SimplePersistedBPMN2ProcessTest that has few test cases with enabled persistence

Objective for this is to ensure there are same tests run with and without persistence to ensure full support for example by moving tests to an abstract class and then execute full suite with both configurations