Add more unit tests for the bpfman-operator

Ideas include:
- Add and delete links
- Delete the BpfApplication and check that things have been cleaned up.
- Negative test cases:
- Add programs to the list in a BpfApplication
- Delete programs from the list in a BpfApplication

Start by locating the existing unit tests and the BpfApplication handling in the bpfman-operator repository. Add coverage for link creation and deletion, cleanup after deleting a BpfApplication, and the listed negative program-list cases. Done means these scenarios are represented by tests and the expected cleanup or rejection behavior is verified.

Written by the indexing model from the issue text.