Disable metrics server in unit tests

Controller manager should not create metrics server in unti tests, as 8080 port
might be already in use when k3d and Redpanda container is created during
operator tests.

```
    pvcunbinder_test.go:348:
        	Error Trace:	/work/src/go/k8s/internal/controller/pvcunbinder/pvcunbinder_test.go:348
        	            				/root/go/pkg/mod/golang.org/[email protected]/src/runtime/asm_amd64.s:1695
        	Error:      	Received unexpected error:
        	            	failed to start metrics server: failed to create listener: listen tcp :8080: bind: address already in use
        	Test:       	TestPVCUnbinder
    pvcunbinder_test.go:237:
        	Error Trace:	/work/src/go/k8s/internal/controller/pvcunbinder/pvcunbinder_test.go:237
        	Error:      	Condition never satisfied
        	Test:       	TestPVCUnbinder
```

src/go/k8s/internal/controller/pvcunbinder/pvcunbinder_test.go

@@ -29,6 +29,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/client"
 	"sigs.k8s.io/controller-runtime/pkg/log"
 	"sigs.k8s.io/controller-runtime/pkg/manager"
+	metricsserver "sigs.k8s.io/controller-runtime/pkg/metrics/server"
 )
 
 func TestPVCUnbinderShouldRemediate(t *testing.T) {
@@ -220,6 +221,7 @@ func TestPVCUnbinder(t *testing.T) {
 
 	// Start up our manager
 	mgr, err := manager.New(cluster.RESTConfig(), manager.Options{
+		Metrics: metricsserver.Options{BindAddress: "0"},
 		BaseContext: func() context.Context {
 			return log.IntoContext(ctx, logger)
 		},