improve: metrics processing e2e test stability (#3244) #6656

Job	Run time
sample_operators_tests (sample-operators/webpage)	3m 13s
sample_operators_tests (sample-operators/tomcat-operator)	2m 50s
sample_operators_tests (sample-operators/leader-election)	3m 23s
sample_operators_tests (sample-operators/metrics-processing)	7m 23s
sample_operators_tests (sample-operators/mysql-schema)	2m 48s
	19m 37s

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