Avoid duplicated Cached promises when invalidating expanded postings cache #10806

Job	Run time
test	15m 52s
build	4m 6s
CodeQL	7m 8s
lint	4m 34s
test-no-race	7m 43s
integration-configs-db	2m 48s
integration (requires_docker)	7m 16s
integration (integration_alertmanager)	4m 18s
integration (integration_backward_compatibility)	10m 24s
integration (integration_memberlist)	7m 52s
integration (integration_querier)	15m 22s
integration (integration_ruler)	5m 35s
integration (integration_query_fuzz)	4m 31s
deploy_website	0s
deploy	0s
	1h 37m 29s

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