Refactor tests for clarity and maintainability #5612

Job	Run time
build-all	3m 22s
tests (hbase, -Dtest="*/diskstorage/hbase/", hbase2-diskstorage-java8, 8)	38m 59s
tests (hbase, -Pjava-11, -Dtest="*/hadoop/", hbase2-hadoop, 11)	35m 52s
tests (hbase, -Pjava-11, -Dtest="*/graphdb/hbase/", hbase2-graphdb, 11)	46m 15s
tests (hbase, -Dtest="*/graphdb/hbase/", hbase2-graphdb-java8, 8)	46m 30s
tests (hbase, -Pjava-11, -Dtest="*/diskstorage/hbase/", hbase2-diskstorage, 11)	44m 25s
tests (hbase, -Dtest="*/hadoop/", hbase2-hadoop-java8, 8)	31m 34s
	4h 6m 57s

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