HBASE-9819 Backport HBASE-8372 'Provide mutability to CompoundConfiguration' to 0.94 (Ted Yu)



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1535442 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8397 improve unit-test coverage of package org.apache.hadoop.hbase.master.metrics (0.94)



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1535452 13f79535-47bb-0310-9956-ffa450edef68
HBASE-8397 Revert due to test failure in secure build



git-svn-id: https://svn.apache.org/repos/asf/hbase/branches/0.94@1535503 13f79535-47bb-0310-9956-ffa450edef68