Use Tempest 'all' tox env

Tempest recently moved tox default
to py3 including all-plugin env.
-https://review.opendev.org/#/c/703011/

This will fail the py2 jobs which are using
all-plugin tox env. Because tox all-plugin
env var enable the sitepackages=True. Py2 jobs
install the tempest plugins on py2 and all-plugin
tox try to find the installed plugins on py3 which
cause no test to run and fail the job.

tox all-plugin has been deprecated since long and not
supposed to use for plugins who already in migrated to
separate repo in queens cycle.

Using tox 'all' env to fix the issue.

Change-Id: Ib1a2be90c0b3dbacc6daf52f0fc6f326ab47fc98
Closes-Bug: 1862240

.zuul.yaml

@@ -15,7 +15,7 @@
         s-object: false
         s-proxy: false
         c-bak: false
-      tox_envlist: all-plugin
+      tox_envlist: all
       tempest_test_regex: |
         designate_tempest_plugin.*
     required-projects: &base_required_projects

playbooks/legacy/grenade-devstack-designate-pdns4/run.yaml

@@ -31,6 +31,7 @@
           [[local|localrc]]
           DESIGNATE_SERVICE_PORT_DNS=5322
           DESIGNATE_BACKEND_DRIVER=pdns4
+          TEMPEST_PLUGINS=' ../designate-tempest-plugin'
 
           EOF
         executable: /bin/bash
@@ -44,7 +45,6 @@
           export PYTHONUNBUFFERED=true
 
           export DEVSTACK_GATE_TEMPEST=1
-          export DEVSTACK_GATE_TEMPEST_ALL_PLUGINS=1
           export DEVSTACK_GATE_GRENADE=pullup
           export DEVSTACK_GATE_TEMPEST_REGEX="designate_tempest_plugin(?!\.tests.api.v1).*"
           export DEVSTACK_GATE_HORIZON=1