End-to-end testing of other core functionalities

A few core functionalities are not being tested in the end-to-end tests. We do not test for the moment the update of a resource for instance.

As such, some further end-to-end tests need to be added:

• Update of resources;
• K8s Custom Resources support;
• "Complete" Hook;
• Prometheus provider;
• Add End-to-end test of the rescheduling