Don't deallocate network if destroy time out

Fixes bug #1169057
Sames as bug 1180178, if libvirt returns time out error during destroy
an instance, we also can't deallocate the network of the instance,
otherwise the fixed ip of it may be re-used by another new instance,
and resulted in the new instance can't be accessed by the fixed ip.

Change-Id: I04dfd21bb1b7168abc71f39e836126a11dad6d8d
(cherry picked from commit d925044e09509495e7474d5f625bbd45d8985afa)
Merge "Don't deallocate network if destroy time out" into stable/grizzly