Switch bagpipe-bgpvpn job to be run using Python3

Depends-On: https://review.opendev.org/686990

Change-Id: I91d71d50df6e254a97e918382c3859220f605531
diff --git a/.zuul.yaml b/.zuul.yaml
index c79e02b..0cbdc33 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -866,7 +866,6 @@
         NETWORKING_BGPVPN_DRIVER: "BGPVPN:BaGPipe:networking_bgpvpn.neutron.services.service_drivers.bagpipe.bagpipe_v2.BaGPipeBGPVPNDriver:default"
         BAGPIPE_DATAPLANE_DRIVER_IPVPN: "ovs"
         BAGPIPE_BGP_PEERS: "-"
-        USE_PYTHON3: false
         NETWORK_API_EXTENSIONS: "{{ (network_api_extensions + network_api_extensions_bgpvpn) | join(',') }}"
       devstack_plugins:
         networking-bgpvpn: https://git.openstack.org/openstack/networking-bgpvpn