Removed unreferenced code (#5935) #14215

Job	Run time
fastbuild	2m 2s
mvn (qa-checks, 17, verify javadoc:jar -Psec-bugs -DskipTests -Dspotbugs.timeout=3600000)	7m 57s
mvn (compat, 17, package -DskipTests -Dversion.hadoop=3.0.3 -Dversion.zookeeper=3.6.4)	1m 30s
mvn (errorprone, 17, verify -Perrorprone,skipQA)	2m 42s
mvn (unit-tests, 17, verify -PskipQA -DskipTests=false)	7m 12s
	21m 23s

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