Zuul: do not use USE_PYTHON3

Devstack has removed the USE_PYTHON3 variable[1][2] and now always uses
Python 3.

[1] https://review.opendev.org/c/openstack/devstack/+/920658
[2] Commit 5412dbfe7b797149f1f68100de8003b1876398fe

Change-Id: I67d390d9681a0274688e58b3bd05946faae59dde

zuul.d/integrated-gate.yaml

@@ -94,7 +94,6 @@
       tempest_concurrency: 4
       tox_envlist: integrated-full
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
         ENABLE_VOLUME_MULTIATTACH: true
         GLANCE_USE_IMPORT_WORKFLOW: True
@@ -146,7 +145,6 @@
     vars:
       tox_envlist: integrated-network
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
       devstack_services:
         s-account: false
@@ -178,7 +176,6 @@
       tox_envlist: integrated-compute
       tempest_exclude_regex: ""
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
         ENABLE_VOLUME_MULTIATTACH: true
       devstack_services:
@@ -224,7 +221,6 @@
       tempest_concurrency: 4
       tox_envlist: integrated-placement
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
         ENABLE_VOLUME_MULTIATTACH: true
       devstack_services:
@@ -244,7 +240,6 @@
     vars:
       tox_envlist: integrated-storage
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
         ENABLE_VOLUME_MULTIATTACH: true
         GLANCE_USE_IMPORT_WORKFLOW: True
@@ -258,11 +253,6 @@
       related tests. This is meant to be run on Swift gate only.
     vars:
       tox_envlist: integrated-object-storage
-      devstack_localrc:
-        # NOTE(gmann): swift is not ready on python3 yet and devstack
-        # install it on python2.7 only. But setting the USE_PYTHON3
-        # for future once swift is ready on py3.
-        USE_PYTHON3: true
 
 - job:
     name: tempest-with-latest-microversion

zuul.d/stable-jobs.yaml

@@ -77,7 +77,6 @@
           (AttachVolumeMultiAttachTest)|\
           (UpdateMultiattachVolumeNegativeTest)"
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
         ENABLE_VOLUME_MULTIATTACH: true
         GLANCE_USE_IMPORT_WORKFLOW: True
@@ -102,10 +101,6 @@
         neutron: https://opendev.org/openstack/neutron
       devstack_services:
         neutron-trunk: true
-    group-vars:
-      subnode:
-        devstack_localrc:
-          USE_PYTHON3: true
 
 - job:
     name: tempest-multinode-full-py3
@@ -119,16 +114,10 @@
       - ^.*/yoga
       - ^.*/zed
     vars:
-      devstack_localrc:
-        USE_PYTHON3: true
       devstack_plugins:
         neutron: https://opendev.org/openstack/neutron
       devstack_services:
         neutron-trunk: true
-    group-vars:
-      subnode:
-        devstack_localrc:
-          USE_PYTHON3: true
 
 - job:
     name: tempest-multinode-full
@@ -145,12 +134,6 @@
           (DHCPAgentSchedulersTestJSON)|\
           (AttachVolumeMultiAttachTest)|\
           (UpdateMultiattachVolumeNegativeTest)"
-      devstack_localrc:
-        USE_PYTHON3: False
-    group-vars:
-      subnode:
-        devstack_localrc:
-          USE_PYTHON3: False
 
 - job:
     name: tempest-multinode-full
@@ -160,13 +143,6 @@
     branches:
       - ^.*/yoga
       - ^.*/zed
-    vars:
-      devstack_localrc:
-        USE_PYTHON3: False
-    group-vars:
-      subnode:
-        devstack_localrc:
-          USE_PYTHON3: False
 
 - job:
     name: tempest-slow-py3

zuul.d/tempest-specific.yaml

@@ -68,7 +68,6 @@
       run_tempest_cleanup: true
       run_tempest_cleanup_prefix: true
       devstack_localrc:
-        USE_PYTHON3: true
         FORCE_CONFIG_DRIVE: true
       devstack_services:
         s-account: false