fix logging error

[DockToFuture]

What this PR does / why we need it:
Fix logging error for health check.

Observed panic:

{"level":"dpanic","ts":"2025-11-25T10:33:53.930Z","logger":"aws-custom-route-controller.controller.node","msg":"odd number of arguments passed as key-value pairs for logging","ignored key":"initialise not started","stacktrace":"github.com/gardener/aws-custom-route-controller/pkg/controller.(*NodeReconciler).HealthzChecker\n\t/build/pkg/controller/reconciler.go:175\nsigs.k8s.io/controller-runtime/pkg/healthz.(*Handler).serveAggregated\n\t/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/healthz/healthz.go:59\nsigs.k8s.io/controller-runtime/pkg/healthz.(*Handler).ServeHTTP\n\t/go/pkg/mod/sigs.k8s.io/[email protected]/pkg/healthz/healthz.go:148\nsigs.k8s.io/controller-runtime/pkg/manager.(*controllerManager).addHealthProbeServer.StripPrefix.func3\n\t/usr/local/go/src/net/http/server.go:2384\nnet/http.HandlerFunc.ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2322\nnet/http.(*ServeMux).ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2861\nnet/http.serverHandler.ServeHTTP\n\t/usr/local/go/src/net/http/server.go:3340\nnet/http.(*conn).serve\n\t/usr/local/go/src/net/http/server.go:2109"}

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Release note:

Fix logging error for health check.

[domdom82]

/lgtm

/approve

[gardener-robot]

@domdom82 Command /approve is not known.