improve: PrimaryUpdateAndCacheUtils naming and javadoc improvements #5154

Job	Run time
sample_operators_tests (sample-operators/webpage)	3m 3s
sample_operators_tests (sample-operators/tomcat-operator)	2m 32s
sample_operators_tests (sample-operators/mysql-schema)	4m 24s
sample_operators_tests (sample-operators/leader-election)	3m 18s
	13m 17s

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