It isn't very practical to have `request_timeout: 300s` for [http-gw](https://github.com/TrueCloudLab/frostfs-dev-env/blob/36f775668d3a6e3ea977f471d937b05f7b9e0dbe/services/http_gate/.http.env#L7). Let's use more appropriate value (could be get from service config example: [http](https://github.com/TrueCloudLab/frostfs-http-gw/blob/master/config/config.yaml), [s3](https://github.com/TrueCloudLab/frostfs-s3-gw/blob/master/config/config.yaml) etc)
