fix(interface): match labels against FQDN in LLDP validation

[nikatza]

In this commit we change the validation of the label against the
information received via LLDP. If DNS is configured on the remote device
via a DNS Kubernetes resource, the interface controller fetches that
resource and uses the domain field together with the device hostname
to build an FQDN that is then compared to the LLDP systemName. This
change now captures devices that export the FQDN in LLDP.

Add DNS watch to interface controller for LLDP neighbor re-validation.
When a DNS resource is created, deleted, or has its domain changed,
interfaces with neighbor labels pointing to that device's interfaces are
re-enqueued so LLDP adjacency validation re-evaluates the expected FQDN.
Also fix SetLLDPNeighbor test helper to set ChassisIDType/PortIDType so
LLDP adjacencies are no longer silently skipped in integration tests.

Replace conditions-length heuristic in interfaceUpdatePredicate with
explicit finalizer and deletion-timestamp checks. Adding a finalizer is
a metadata-only change that no standard predicate (Generation, Label,
Annotation) catches, so it falls to interfaceUpdatePredicate. The old
len(conditions) < 4 guard happened to let these through because
conditions are empty during bootstrap, but expressed the wrong
invariant. The new checks explicitly pass the lifecycle transitions that
the controller's multi-step bootstrap (finalizer → init conditions →
reconcile) depends on.

[github-actions]

Merging this branch will increase overall coverage

Impacted Packages	Coverage Δ	🤖
github.com/ironcore-dev/network-operator/internal/controller/core	63.84% (+1.18%)	👍

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Coverage by file

Changed files (no unit tests)

Changed File	Coverage Δ	Total	Covered	Missed	🤖
github.com/ironcore-dev/network-operator/internal/controller/core/interface_controller.go	72.60% (+6.72%)	584 (+33)	424 (+61)	160 (-28)	👍

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/ironcore-dev/network-operator/internal/controller/core/interface_controller_test.go
• github.com/ironcore-dev/network-operator/internal/controller/core/suite_test.go