Time out async sends to avoid slackers stuck in the queue for too long (backport #28545)

[mergify]

This is an automatic backport of pull request #28545 done by Mergify.
Cherry-pick of f10ef76 has failed:

On branch mergify/bp/v1.14/pr-28545
Your branch is up to date with 'origin/v1.14'.

You are currently cherry-picking commit f10ef763d.
  (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:   client/src/nonblocking/quic_client.rs
	modified:   client/src/quic_client.rs
	modified:   client/src/tpu_connection.rs

Unmerged paths:
  (use "git add/rm <file>..." as appropriate to mark resolution)
	deleted by us:   tpu-client/src/connection_cache_stats.rs

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

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[solana-grimes]

😱 New commits were pushed while the automerge label was present.