Add distributor per labelset received samples metric #10769

Job	Run time
lint	4m 20s
build	4m 11s
CodeQL	7m 7s
test	15m 44s
test-no-race	7m 57s
integration-configs-db	3m 20s
integration (requires_docker)	7m 29s
integration (integration_alertmanager)	4m 32s
integration (integration_backward_compatibility)	11m 11s
integration (integration_memberlist)	7m 31s
integration (integration_querier)	15m 27s
integration (integration_ruler)	5m 38s
integration (integration_query_fuzz)	5m 17s
deploy_website	0s
deploy	0s
	1h 39m 44s

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