Remove grpc-gateway

[fbac]

Remove the HTTP gateway and construct replication and API servers to serve only gRPC across cmd/replication, pkg/api, pkg/server, and related scripts and tests

This change removes the grpc-gateway HTTP layer across the replication service, API server, builders, configs, and tests, leaving only gRPC listeners and related options. Key updates include deletion of the HTTP server implementation, removal of HTTP listener/registration options and fields, and updates to dev scripts and tests to stop configuring HTTP ports.

• Delete HTTP gateway implementation in http_server.go and remove all HTTP listener/registration handling in server.go
• Update replication entrypoint to construct only a gRPC listener in main.go
• Drop HTTP port from API config in options.go
• Build the gateway service without HTTP registration or listener in builder.go
• Remove HTTP-related server config and startup in server.go
• Adjust dev scripts to omit --api.http-port in run-2 and run-gateway
• Update tests and test utils to use only gRPC across builder_unit_test.go, integration_test.go, server_test.go, envelopes_generator_test.go, api.go, and server.go

📍Where to Start

Start at api.NewAPIServer in server.go, then follow server.startAPIServer in server.go and the replication main in main.go.

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Macroscope summarized 6f3c809.

[graphite-app]

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[mkysel]

red lines are always good