Update HC type only after deleting old instance
Update HC type only after deleting old instance

While changing the HC type, call destroy with the old type so that
the it is cleaned up.

Change-Id: I6e2daa2e3009adcc513ae5e6549c27a76e43e200
closes-bug: #1732600
(cherry picked from commit 51657d1802ce85dbaf41a0fa0696b7743c882b74)

rombie/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller