Refactor tests for clarity and maintainability #5614

Job	Run time
build-all	3m 19s
tests (hbase, -Pjava-11, -Dtest="*/hadoop/", hbase2-hadoop, 11)	28m 30s
tests (hbase, -Dtest="*/graphdb/hbase/", hbase2-graphdb-java8, 8)	45m 4s
tests (hbase, -Dtest="*/hadoop/", hbase2-hadoop-java8, 8)	19m 37s
tests (hbase, -Pjava-11, -Dtest="*/diskstorage/hbase/", hbase2-diskstorage, 11)	33m 2s
tests (hbase, -Dtest="*/diskstorage/hbase/", hbase2-diskstorage-java8, 8)	31m 59s
tests (hbase, -Pjava-11, -Dtest="*/graphdb/hbase/", hbase2-graphdb, 11)	33m 42s
	3h 15m 13s

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