Make time out 60 mins like the Heat default.

Make the overcloud create timeout match that of the Heat default
(60 mins for the Heat stack-create), as on slow networks with real
hardware the set-up time can be slow. Also if the stack-create
fails the loop will exit so this change should be harmless.

Change-Id: I5641aab4d69ba92dea81f06bdda51d46a113e814
Merge "Make time out 60 mins like the Heat default."