Prepare release 1.19.0-rc.1 #11111

Job	Run time
test	16m 2s
test-no-race	7m 44s
lint	4m 26s
build	4m 13s
CodeQL	6m 47s
integration (requires_docker)	7m 0s
integration-configs-db	2m 45s
integration (integration_alertmanager)	4m 15s
integration (integration_backward_compatibility)	10m 34s
integration (integration_memberlist)	7m 14s
integration (integration_querier)	15m 11s
integration (integration_ruler)	5m 47s
integration (integration_query_fuzz)	4m 35s
deploy_website	0s
deploy	0s
	1h 36m 33s

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