Fix potential kwargs deprecation in ConnectionProxy

Via @engwan:

Found something in our DB load balancer that might need fixing. I got some deprecation errors when I attempted to change some specs to actually use DB load balancing (Right now they're just mocking #enabled? calls, etc..)

The methods we define in ConnectionProxy only passes through *args and not **kwargs.

We need to pass keyword args too since some ActiveRecord methods like #transaction accept keyword arguments.