feat: shard selector support #7358

Job	Run time
sample_operators_tests (sample-operators/mysql-schema)	3m 37s
sample_operators_tests (sample-operators/leader-election)	4m 16s
sample_operators_tests (sample-operators/webpage)	4m 5s
sample_operators_tests (sample-operators/operations)	9m 47s
sample_operators_tests (sample-operators/tomcat-operator)	3m 51s
	25m 36s

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