Normalize tests on SpecContext in leaf

[fwiesel]

The tests before where partly relying one a global context, which means
the cancelation from ginkgo wasn't really passed down. The leaf
functions can take a context.Context or SpecContext argument. The latter
is already imported, so lets go with that one.

[github-actions]

Merging this branch will not change overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller	49.01% (ø)

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Coverage by file

Changed unit test files

• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/aggregates_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/decomission_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/eviction_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/gardener_node_lifecycle_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/hypervisor_maintenance_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/node_certificate_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/node_eviction_label_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/onboarding_controller_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/suite_test.go
• github.com/cobaltcore-dev/openstack-hypervisor-operator/internal/controller/traits_controller_test.go