Ensure parameter timeout_mins available in update

The parameter timeout_mins is not available when
updating a stack. The updater gets it from the
old stack no matter whether timeout_mins is
offered or not.

If timeout_mins is not offered in the new stack,
get the timeout from the old stack, and update
this parameter using the new stack's timeout.

Change-Id: I7d04d0f0b7cc917d49d45c0d3e1d5a8ffb7bff0b
Closes-Bug: 1290603
Merge "Ensure parameter timeout_mins available in update"