HBASE-20169 NPE when calling HBTU.shutdownMiniCluster
Adds a prepare step to RecoverMetaProcedure in which we test for
cluster up and master being up. If not up, we fail the run.
Modified hbase-server/src/main/java/org/apache/hadoop/hbase/master/cleaner/HFileCleaner.java
Modified hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/ChunkCreator.java
Minor log cleanup.
Modified hbase-server/src/main/java/org/apache/hadoop/hbase/master/procedure/RecoverMetaProcedure.java
Add pepare step.
Modified hbase-server/src/test/java/org/apache/hadoop/hbase/master/TestAssignmentManagerMetrics.java
Debug for the failing test....
Added hbase-server/src/test/java/org/apache/hadoop/hbase/master/procedure/TestRecoverMetaProcedure.java
Test the prepare step goes down if master or cluster are down.