pass prefer_socket=false is not effective

[ouyanglin886]

I have a server that is using the TDSQL for MySQL distribution database provided by Tencent Cloud.The TDSQL it's not support @@socket variable, but when I pass prefer_socket=false, he doesn't take effect。I think it may be caused by the following code：

    let settings: Option<Row> = if read_socket || read_max_allowed_packet || read_wait_timeout {
        self.query_internal("SELECT @@socket, @@max_allowed_packet, @@wait_timeout")
            .await?
    } else {
        None
    };

it's modify history:

[blackbeam]

Fixed in v0.33.0