node/gointerfaces/grpcutil: unify grpc server bring-up across daemons

[yperbasis]

cmd/downloader, txnprovider/txpool, node/privateapi, and p2p/sentry each re-inlined the interceptor/keepalive option block that grpcutil.NewServer already builds — two of them complete with its dead commented-out metrics hooks — and all four repeated the same listen + health-server + serve-goroutine tail.

NewServer(rateLimit, creds) now delegates to a new NewServerWithOpts(creds, extraOpts...) (nil-safe creds, no forced MaxConcurrentStreams), and StartServer/StartServerOnListener own the listen/health/serve tail. The four sites convert onto these.

Option preservation was the review focus, per site: downloader and txpool still run without MaxConcurrentStreams (as before); txpool keeps its explicit ReadBufferSize(0)/WriteBufferSize(0); privateapi/sentry keep health registration gated on their healthCheck flag while downloader/txpool keep it unconditional; existing NewServer callers see byte-identical behavior.

Two deliberate exceptions to strict preservation:

• Both converted StartGrpcs now take credentials.TransportCredentials by value (as privateapi.StartGrpc already does) instead of pointer-to-interface, dropping the identical unwrap shim at each site; their sole callers pass literal nil and are unchanged.
• The txpool serve-failure log now reads txpool gRPC server fail instead of the private RPC server fail string copy-pasted from privateapi — in the standalone txpool daemon, --private.api.addr names the remote node it connects to, so the old label pointed triage at the wrong process. Nothing greps or asserts these strings.

Otherwise no behavior change — existing tests are the safety net (txpool, privateapi, sentry suites green). Full make lint clean, make erigon integration build. Net −117 lines.

Part of a dedup series; siblings #22165–#22170.

[Copilot]

Pull request overview

Refactors gRPC server initialization across multiple daemons to remove duplicated option/interceptor/keepalive blocks and centralize the common listen + (optional) health server + serve-goroutine startup logic in grpcutil.

Changes:

• Added grpcutil.NewServerWithOpts for composing a standard server with optional extra grpc.ServerOptions (and nil-safe creds handling).
• Added grpcutil.StartServer / StartServerOnListener to own the common listener + health registration + Serve goroutine tail.
• Updated downloader, txpool, privateapi, and sentry to use the unified helpers while preserving per-site option differences (e.g., txpool buffer sizes, healthCheck gating).

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
node/gointerfaces/grpcutil/utils.go	Introduces NewServerWithOpts and shared StartServer* helpers for consistent gRPC bring-up.
cmd/downloader/main.go	Switches downloader gRPC startup to grpcutil.NewServerWithOpts + grpcutil.StartServer.
txnprovider/txpool/txpool_grpc_server.go	Switches txpool gRPC startup to grpcutil.NewServerWithOpts (preserving buffer opts) + grpcutil.StartServer.
node/privateapi/all.go	Switches privateapi server startup to grpcutil.StartServer (preserving healthCheck gating).
p2p/sentry/sentry_grpc_server.go	Switches sentry server startup tail to grpcutil.StartServerOnListener (preserving custom listen config + healthCheck gating).

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[Copilot]

Pull request overview

Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.