cleanup: replace dial with newclient #13192

Job	Run time
vet-proto	35s
vet-proto	35s
tests (vet, 1.22)	1m 15s
tests (vet, 1.22)	1m 15s
tests (extras, 1.23)	3m 5s
tests (extras, 1.23)	3m 5s
tests (tests, 1.23)	4m 6s
tests (tests, 1.23)	4m 6s
tests (tests, 1.23, -race)	5m 36s
tests (tests, 1.23, -race)	5m 36s
tests (tests, 1.23, 386)	4m 48s
tests (tests, 1.23, 386)	4m 48s
tests (tests, 1.23, arm64)	6m 38s
tests (tests, 1.23, arm64)	6m 38s
tests (tests, 1.22)	3m 31s
tests (tests, 1.22)	3m 31s
tests (tests, 1.23, -race, GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST=true)	4m 51s
tests (tests, 1.23, -race, GRPC_EXPERIMENTAL_ENABLE_NEW_PICK_FIRST=true)	5m 0s
	1h 8m 59s

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