Add tpu-client-next to `SendTransactionService` #12646

Job	Run time
cargo-test-sbf (token/program)	8m 8s
cargo-test-sbf (instruction-padding/program, token/program-2022, token/program-2022-test)	14m 5s
check	4m 33s
cargo-test-sbf (associated-token-account/program, associated-token-account/program-test)	9m 46s
test (token/cli, token/program, token/program-2022, associated-token-account/program, instruction...	19m 1s
test (single-pool/cli, single-pool/program)	21m 10s
cargo-test-sbf (token-upgrade/program)	8m 55s
test (token-upgrade/cli, token-upgrade/program)	15m 38s
cargo-test-sbf (feature-proposal/program)	7m 46s
cargo-test-sbf (governance/addin-mock/program, governance/program)	12m 19s
cargo-test-sbf (memo/program)	8m 20s
cargo-test-sbf (name-service/program)	8m 11s
cargo-test-sbf (stake-pool/program)	11m 27s
cargo-test-sbf (single-pool/program)	10m 33s
	2h 39m 52s

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