Support failing tests in validate* methods when certain errors appear for longer than a desired threshold

[squizzi]

Currently we have a few validations like this one:

	if cluster != nil {
		phase, _, _ := unstructured.NestedString(cluster.Object, "status", "phase")
		if phase != "Deleting" {
			return fmt.Errorf("cluster: %q exists, but is not in 'Deleting' phase", clusterName)
		}

Where we are trying to validate a deletion and are waiting on a certain phase. In instances like this it doesn't make sense to spend 90m waiting for the cluster to enter 'Deleting' phase, instead we should probably only wait 60s here. It'd be nice to support a threshold where we call Fail after hitting a state that should exist for some time but not for a long time.