Bump default idleConnsPerHost to control conns in time_wait (#10653)

This PR fixes a hang which occurs quite commonly at higher concurrency
by allowing following changes

- allowing lower connections in time_wait allows faster socket open's
- lower idle connection timeout to ensure that we let kernel
  reclaim the time_wait connections quickly
- increase somaxconn to 4096 instead of 2048 to allow larger tcp
  syn backlogs.

fixes #10413

cmd/endpoint.go

@@ -771,11 +771,7 @@ func GetProxyEndpoints(endpointZones EndpointZones) ([]ProxyEndpoint, error) {
 			}
 
 			// allow transport to be HTTP/1.1 for proxying.
-			tr := newCustomHTTP11Transport(tlsConfig, rest.DefaultTimeout)()
-
-			// Allow more requests to be in flight with higher response header timeout.
-			tr.ResponseHeaderTimeout = 30 * time.Minute
-			tr.MaxIdleConnsPerHost = 64
+			tr := newCustomHTTPProxyTransport(tlsConfig, rest.DefaultTimeout)()
 
 			proxyEps = append(proxyEps, ProxyEndpoint{
 				Endpoint:  endpoint,