HBASE-12010 Use TableName.META_TABLE_NAME instead of indirectly from HTableDescriptor

Conflicts:
	hbase-server/src/main/java/org/apache/hadoop/hbase/util/FSTableDescriptors.java
	hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/wal/TestLogRollingNoCluster.java