[ST]: handle gracefully if VMI is deleted while allocating service interface ip
[ST]: handle gracefully if VMI is deleted while allocating service interface ip

Change-Id: I7afcc2aa70dde8b117fd6ffb5fada011325c0f21
Closes-Bug: #1611064

codilime/contrail-controller,codilime/contrail-controller,codilime/contrail-controller,codilime/contrail-controller,codilime/contrail-controller,codilime/contrail-controller