[Feature] Improved Testability for local development and CI pipelines

[SimonBaeumer]

Problem Currently we struggle testing the operator with OLM. OLM adds more capabilities, i.e. pre-flight checks, and caused an incident in an ACS release. It is hard to test operator changes due to the complexity of different OLM CRs (subscription, install plans, CSV, catalog) interacting with each other. Having a process to test the upgrade logics easy would be great and simplify our development process significantly.