OutlierDetection does not provide a Status description when ejecting

[ejona86]

Although RPCs should not fail because of OutlierDetection, as it makes sure there are still some working addresses, passing down a Status without a description can make debugging hard:

grpc-java/util/src/main/java/io/grpc/util/OutlierDetectionLoadBalancer.java

Lines 328 to 329 in bdb0c72

	subchannelStateListener.onSubchannelState(
	ConnectivityStateInfo.forTransientFailure(Status.UNAVAILABLE));

A hard-coded description would be really easy and make things more clear.