restore gateway default conn timeout behavior

Originally, the behavior was altered because it was assumed that the gateway could be reusing conns during Dial. This was a misunderstanding, some http frameworks will reuse conns but the standard dialer.Dial will not (from my best understanding).

It turns out that other techniques were responsible for fixing the gateway desync issues, not this particular change.

I have run some tests in the antfarm, and it seems like reverting this change has not re-introduced the desynchronization that we were struggling with earlier.