The NSX-V3 driver for LBaaSv2 & Octavia does not support multiple
listeners for the same pool.
This code handles create/update of pool with multiple listeners, and also
create/update of listener with a default pool that is already in use.
For that there is also a need to update the pool DB mapping also when
added/removed to a listener.
Additional related code for session persistence support will be added in
a follow up patch.
Change-Id: Id121d12cad16825e4e760f607f811bf92ce02d33
3ff350ac24