Reduce binary size with field-level conditional compilation for protobuf messages (#9473)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

esphome/components/api/api_connection.cpp

@@ -1463,7 +1463,9 @@ DeviceInfoResponse APIConnection::device_info(const DeviceInfoRequest &msg) {
 #endif
   resp.name = App.get_name();
   resp.friendly_name = App.get_friendly_name();
+#ifdef USE_AREAS
   resp.suggested_area = App.get_area();
+#endif
   resp.mac_address = get_mac_address_pretty();
   resp.esphome_version = ESPHOME_VERSION;
   resp.compilation_time = App.get_compilation_time();