fix: stop thread pools when an error occurs during startup #6083

Job	Run time
sample_operators_tests (sample-operators/mysql-schema)	2m 56s
sample_operators_tests (sample-operators/leader-election)	3m 17s
sample_operators_tests (sample-operators/tomcat-operator)	2m 59s
sample_operators_tests (sample-operators/webpage)	3m 3s
	12m 15s

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