tests: allow customizing the start timeout
tests: allow customizing the start timeout

For times that we know the watchman instance won't come up, waiting for a
second seems pointless.

wez/watchman,wez/watchman,nodakai/watchman,dhruvsinghal/watchman,nodakai/watchman,dhruvsinghal/watchman,facebook/watchman,facebook/watchman,kwlzn/watchman,facebook/watchman,dhruvsinghal/watchman,dhruvsinghal/watchman,dhruvsinghal/watchman,nodakai/watchman,wez/watchman,wez/watchman,facebook/watchman,kwlzn/watchman,kwlzn/watchman,dhruvsinghal/watchman,wez/watchman,wez/watchman,nodakai/watchman,nodakai/watchman,nodakai/watchman,dhruvsinghal/watchman,nodakai/watchman,facebook/watchman,wez/watchman,facebook/watchman,nodakai/watchman,kwlzn/watchman,kwlzn/watchman,dhruvsinghal/watchman,wez/watchman,facebook/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,wez/watchman,kwlzn/watchman,kwlzn/watchman