feat: add experimental annotation (#2853) #5542

Job	Run time
sample_operators_tests (sample-operators/leader-election)	3m 37s
sample_operators_tests (sample-operators/mysql-schema)	3m 1s
sample_operators_tests (sample-operators/webpage)	3m 14s
sample_operators_tests (sample-operators/tomcat-operator)	3m 29s
	13m 21s

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