Fail faster on connection termination

Summary:
If a connection is killed (overloaded or primary step down), only retry
once and don't sleep in between. This should let the system recover more
quickly from problems by failing faster.

Test Plan:
Simulated failures locally, but I'll watch closely tomorrow when I have
to step down a lot of primaries in prod.

Reviewers: josh

Maniphest Tasks: T10877

Differential Revision: http://phab.wish.com/D15710