improve: metrics processing e2e test stability #6652

Job	Run time
sample_operators_tests (sample-operators/leader-election)	3m 15s
sample_operators_tests (sample-operators/metrics-processing)	7m 28s
sample_operators_tests (sample-operators/tomcat-operator)	2m 52s
sample_operators_tests (sample-operators/webpage)	2m 59s
sample_operators_tests (sample-operators/mysql-schema)	2m 37s
	19m 11s

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