Fix for the issue that an amphorav2 LB cannot be reached after
loadbalancer failover. The LB security group was not set in the
amphora port.
Fixed the v2 variant of UpdateVIPSecurityGroup to actually return the
security group id (v1 already did).
The flow created in get_failover_LB_flow uses UpdateVIPSecurityGroup
which is supposed to provide VIP_SG_ID, which is later needed in
get_amphora_for_lb_failover_subflow as a requirement for
CreateVIPBasePort.
Story: 2008735
Task: 42087
Change-Id: I1bb334ef0c11a79038b21a873a6675d76b0fbefc
(cherry picked from commit 0513319f3d)
e3b68219dd