v2.1: use tpu-client-next in send_transaction_service (backport of #3515)

[mergify]

Problem

This PR adds tpu-client-next to send_transaction_service as an optional client.

Summary of Changes

---

This is an automatic backport of pull request #3515 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 5c0f173 has failed:

On branch mergify/bp/v2.1/pr-3515
Your branch is up to date with 'origin/v2.1'.

You are currently cherry-picking commit 5c0f173b88.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   Cargo.lock
	modified:   rpc/src/cluster_tpu_info.rs
	modified:   send-transaction-service/Cargo.toml
	modified:   send-transaction-service/src/lib.rs
	new file:   send-transaction-service/src/test_utils.rs
	modified:   tpu-client-next/src/connection_workers_scheduler.rs
	modified:   tpu-client-next/src/quic_networking.rs
	modified:   tpu-client-next/src/quic_networking/quic_client_certificate.rs
	modified:   tpu-client-next/tests/connection_workers_scheduler_test.rs

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	both modified:   banks-server/src/banks_server.rs
	both modified:   programs/sbf/Cargo.lock
	both modified:   rpc/src/rpc.rs
	both modified:   rpc/src/rpc_service.rs
	both modified:   send-transaction-service/src/send_transaction_service.rs
	both modified:   send-transaction-service/src/tpu_info.rs
	deleted by us:   send-transaction-service/src/transaction_client.rs
	deleted by us:   svm/examples/Cargo.lock

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

If this PR represents a change to the public RPC API:

1. Make sure it includes a complementary update to rpc-client/ (example)
2. Open a follow-up PR to update the JavaScript client @solana/web3.js (example)

Thank you for keeping the RPC clients in sync with the server API @mergify[bot].

[KirillLykov]

it is failed because we haven't backported yet #3480

[KirillLykov]

Closed in favor of redoing this PR, see #3454 (comment)