HBASE-9914 Port fix for HBASE-9836 'Intermittent TestRegionObserverScannerOpenHook#testRegionObserverCompactionTimeStacking failure' to 0.94 (Takeshi Miao)



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1572166 13f79535-47bb-0310-9956-ffa450edef68