Eviction: Use hypervisor cro instead of searching

[fwiesel]

On top of #213

The hypervisor cro has the hypervisor-id, so let's use that one
instead of looking it up via the name.

[github-actions]

Merging this branch will increase overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller	49.62% (+0.33%)	👍

---

Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/eviction_controller.go	37.73% (+0.93%)	220 (-11)	83 (-2)	137 (-9)	👍

Please note that the "Total", "Covered", and "Missed" counts above refer to code statements instead of lines of code. The value in brackets refers to the test coverage of that file in the old version of the code.

Changed unit test files

• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/eviction_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/onboarding_controller_test.go