Ref T2787. For test charges, Paypal is putting the charge in a "payment review" state. Dealing with this state requires way more infrastructure than other providers: we're supposed to pause delivery, then poll Paypal every 6 hours to see if the review has resolved.
Since I can't seem to generate normal test charges, I can't test Paypal for now. Disable it until we have more infrastructure.
(This diff gets us further along, up to the point where I hit this issue.)
