Adds a Gauge and Counter to CoordinatorEventBlockingQueue. The Gauge tracks the current size of the underlying queue; and the Counter increments when a duplicate event is put(). The class implements MetricsAware and registers the underlying metrics to the simple class name + constructor parameter key. The existing parameterless constructor is marked deprecated. It registers metrics to the key "CoordinatorEventBlockingQueue.legacy".

The change to MetricTestUtils was required to avoid collisions with TestCoordinator. The startsWith predicate was changed to match to ensure that the entire name was used to filter. The same metric verification registration test was added to the CoordinatorEventBlockingQueue.