Merge "Zuul: do not use USE_PYTHON3"

Author: Zuul

zuul.d/base.yaml

@@ -82,7 +82,6 @@
         Q_ML2_PLUGIN_MECHANISM_DRIVERS: ovn
         Q_ML2_PLUGIN_TYPE_DRIVERS: local,flat,vlan,geneve
         Q_ML2_TENANT_NETWORK_TYPE: geneve
-        USE_PYTHON3: True
         TEMPEST_PLUGINS: '/opt/stack/octavia-tempest-plugin'
         OCTAVIA_NODE: api
         OCTAVIA_TEMPEST_PLUGIN_CUSTOMIZE_IMAGE: true