Missing TCP_NODELAY on HttpConnector causes ~40ms latency per gRPC call on localhost with in-memory kurrentdb

[screwyprof]

Problem

NodeConnection::new creates an HttpConnector without setting TCP_NODELAY (grpc.rs:897-898). Nagle's algorithm buffers
small gRPC requests for up to 40ms before sending.

This affects every gRPC call through the client — reads, appends, subscriptions.

Benchmark

Measured read_stream on a nonexistent stream (localhost, single-node, tls=false):

	median	fastest
before (Nagle on)	42 ms	40 ms
after (set_nodelay(true))	311 µs	225 µs

135x improvement. The DB itself responds in ~1ms (verified via HTTP API).

Suggested fix

let mut http = HttpConnector::new();
http.enforce_http(false);
http.set_nodelay(true);  // disable Nagle — gRPC is latency-sensitive

Most gRPC clients set it - Go's gRPC does, Java's does, tonic's built-in transport::Channel sets TCP_NODELAY by default.
The custom hyper client path misses it.

[linear-code]

DEV-1765