fix: time unit in PeriodicCleanerExpectationManager and integration test #6033

Job	Run time
sample_operators_tests (sample-operators/webpage)	3m 12s
sample_operators_tests (sample-operators/mysql-schema)	2m 51s
sample_operators_tests (sample-operators/leader-election)	3m 22s
sample_operators_tests (sample-operators/tomcat-operator)	3m 1s
	12m 26s

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