Fix wifi disable during restore

The main looper needs to run freely for a moment after disabling
wifi in order for various signals (content observers, broadcast) to
propagate to all the listeners that need to take action for the
wifi stack to shut all the way down.  This patch breaks up the
disable-and-rewrite-config sequence of wifi AP restore in to two
distinct operations separated by a moment so as not to block those
necessary messages.

Bug 22979342

Change-Id: I271766cad0e454669a194652fb67f835bb022cd1