devstack: Remove USE_PYTHON3

It's all Python 3 now, baby.

Signed-off-by: Stephen Finucane <stephenfin@redhat.com>

Author: stephenfin

tests/playbooks/roles/install-devstack/templates/local.conf.j2

@@ -3,7 +3,6 @@ RECLONE=False
 HOST_IP={{ local_ip_address }}
 DEST=/opt/stack
 DATA_DIR=${DEST}/data
-USE_PYTHON3=True
 LOGFILE=$DEST/logs/stack.sh.log
 VERBOSE=True
 LOG_COLOR=False