Bump up sleep when expecting a timeout

It seemed like some of the tests ment to exercise the proxy's timeout could
would occastionally race and the backend mock would be able to cough up a
chunk before the timeout fired in the proxy - typically resulting in a failed
assertion like " lalala" != 'lalala'.

We paramaterize the timeout value, and bump it up for those cases where we are
expecting to hit the timeout.  Timing shows this change is just as fast for
passing tests.  And if you want to break the node_timeout in
proxy.controller.base you can verify the tests are still just as effective -
if a bit slower to detect the failure path.

Fixes bug #1272509

Change-Id: Iaf91d9d551e94fc317a08e8c0ee02daeed331b60
Merge "Bump up sleep when expecting a timeout"