Default timeouts of 900 and 1500 seconds which are suitable for
upstream CI are too long for downstream CI causing redundant
15 minutes retries while 2-3 minutes are enough to make a decision
that something went wrong. This patch allows
configuring custom values for ubuntu vm connectivity timeouts.
Change-Id: If33991b0b932d7615f7072a4c2121fde4d5bcdc8
6bc9c6eff7