starknet_transaction_prover: extract the TLS accept loop and test its drain

[avi-starkware]

No description provided.

[reviewable-StarkWare]

This change is 

[avi-starkware]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• starknet_transaction_prover: log resolved config at startup (secrets redacted) #14684
• starknet_transaction_prover: origin-level breadcrumbs for validation errors #14172
• starknet_transaction_prover: /health returns 503 when service is saturated #14171
• starknet_transaction_prover: track saturation and queue depth on the request path #15027
• starknet_transaction_prover: bump prover_panics_total on panic hook fire #14170
• starknet_transaction_prover: HTTP request count + latency + in-flight metrics #14169
• starknet_transaction_prover: proving-job duration + outcome metrics #14168
• starknet_transaction_prover: Prometheus /metrics endpoint with build_info #14167
• starknet_transaction_prover: extract the TLS accept loop and test its drain #15049 👈 (View in Graphite)
• starknet_transaction_prover: graceful shutdown on SIGTERM/SIGINT #15026
• starknet_transaction_prover: global panic hook with structured log #14166
• starknet_transaction_prover: document existing logging, request ids and health probe in README #14203
• main-v0.14.4

This stack of pull requests is managed by Graphite. Learn more about stacking.

[einat-starkware]

@einat-starkware reviewed 2 files and all commit messages, and made 1 comment.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on avi-starkware).

[cursor]

PR Summary

Medium Risk
Touches server accept/shutdown wiring for the transaction prover; incorrect StopHandle sharing could drop in-flight proofs on stop, though behavior is intended to stay the same and is now covered by a regression test.

Overview
Refactors HTTPS JSON-RPC startup by extracting the TCP accept loop into a generic spawn_accept_loop, with a prepare_stream hook that turns each accepted socket into the stream served by jsonrpsee (TLS handshake in start_tls_server, or plain TCP in tests).

Shutdown behavior is documented explicitly: each connection’s service keeps a StopHandle clone so ServerHandle::stopped() stays pending until in-flight requests finish.

Adds tls_test.rs, which drives spawn_accept_loop over HTTP without certificates and asserts that stop() does not let stopped() complete while a parked RPC is still running, then completes after the handler is released.

^{Reviewed by Cursor Bugbot for commit bdc52bd. Bugbot is set up for automated code reviews on this repo. Configure here.}