For Thrift client, use client-only timeouts
For Thrift client, use client-only timeouts

Summary:
We don't want the memcache Thrift server to normally enforce server-side
timeouts (just client side), since
  - the timer instantiation cost is a significant cost (~10%?).
  - we don't actually ever queue, since work happens on the EventBase,
    so it's not really possible for the timeout to fire on the server.

We could just disable on the server side, but the advantage of doing
such on the client side is that we can also avoid serializing the timeout
metadata ints over the wire.

Reviewed By: yfeldblum, andreazevedo

Differential Revision: D15400925

fbshipit-source-id: 1f05a6677f4e32281b5e8202c6f780554a7820d8

facebook/mcrouter,facebook/mcrouter,facebook/mcrouter,facebook/mcrouter