Disable Nagle's algorithm for TLS connections by default

This commit ensures that Nagle's algorithm is disabled by default for
TLS connections on best effort basis, just like other networking
software (e.g. NGINX) does, as, in the case of TLS, we are not
interested in trading latency for throughput, rather vice versa.

We attempt to disable it as early as we can, right after TCP
connections establishment, as an attempt to speed up handshake
handling.

lib/isc/netmgr/netmgr.c

@@ -3030,6 +3030,9 @@ isc_nmhandle_set_tcp_nodelay(isc_nmhandle_t *handle, const bool value) {
 		result = isc__nm_socket_tcp_nodelay((uv_os_sock_t)tcp_fd,
 						    value);
 	} break;
+	case isc_nm_tlssocket:
+		result = isc__nmhandle_tls_set_tcp_nodelay(handle, value);
+		break;
 	default:
 		UNREACHABLE();
 		break;