CLOUDSTACK-6824: In case there is a failure to delete the soft link of a download url, dont bail out since there can be cases such as destroy ssvm where the soft links do not exist any more.
CLOUDSTACK-5505: if vpc public network with snat enabled, then will triger this issue

(cherry picked from commit 5e80e5d33d9a295b91cdba9377f52d9d963d802a)