tracking: Reduce technical debt

[Techassi]

Evolution not revolution!

Pull tasks from here every now and then. Gather tech debt items here.

### Tasks
- [ ] https://github.com/stackabletech/operator-rs/pull/761
- [ ] Improve doc comments / `schemars` descriptions for our CRDs
- [ ] test coverage is often bad
- [ ] Add tests / assertions for generated X.509 certificates (extensions)
- [ ] Generalize string formatting for `product_logging::LogLevel` (or remove `product_logging` entirely)