support singleflight to memcached and redis client set #13443

Job	Run time
Go build for different platforms	8m 9s
Go build for different platforms	8m 9s
Thanos end-to-end tests (8, 0)	4m 27s
Thanos end-to-end tests (8, 0)	4m 27s
Linters (Static Analysis) for Go	1m 15s
Linters (Static Analysis) for Go	1m 15s
Thanos end-to-end tests (8, 1)	3m 27s
Thanos end-to-end tests (8, 1)	3m 27s
Thanos end-to-end tests (8, 2)	3m 41s
Thanos end-to-end tests (8, 2)	3m 41s
Thanos end-to-end tests (8, 3)	3m 49s
Thanos end-to-end tests (8, 3)	3m 49s
Thanos end-to-end tests (8, 4)	6m 46s
Thanos end-to-end tests (8, 4)	6m 46s
Thanos end-to-end tests (8, 5)	3m 18s
Thanos end-to-end tests (8, 5)	4m 9s
Thanos end-to-end tests (8, 6)	3m 30s
Thanos end-to-end tests (8, 6)	3m 30s
Thanos end-to-end tests (8, 7)	3m 17s
Thanos end-to-end tests (8, 7)	3m 17s
	1h 24m 9s

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