tox: Drop envdir

tox now always recreates an env although the env is shared using envdir
options.
~~~
$ tox -e genpolicy
genpolicy: recreate env because env type changed from
{'name': 'genconfig', 'type': 'VirtualEnvRunner'} to
{'name': 'genpolicy', 'type': 'VirtualEnvRunner'}
~~~

According to the maintainer of tox, this functionality is not intended
to be supported.
https://github.com/tox-dev/tox/issues/425#issuecomment-1011944293

Change-Id: Ibda3bf5547b3530f854c667140699ecc8486ee85

tox.ini

@@ -31,11 +31,9 @@ commands =
   bash {toxinidir}/tools/unit_tests.sh {toxinidir} {posargs}
 
 [testenv:venv]
-envdir = {toxworkdir}/venv
 commands = {posargs}
 
 [testenv:pep8]
-envdir = {toxworkdir}/linters
 deps =
   {[testenv]deps}
   flake8-import-order==0.12 # LGPLv3
@@ -50,7 +48,6 @@ commands =
   pylint -j 4 --verbose --rcfile=.pylintrc -f colorized openstack_dashboard openstack_auth horizon
 
 [testenv:cover]
-envdir = {toxworkdir}/venv
 allowlist_externals =
   bash
 commands =
@@ -61,7 +58,6 @@ commands =
   coverage report --show-missing --skip-covered
 
 [testenv:selenium]
-envdir = {toxworkdir}/venv
 setenv =
   {[testenv]setenv}
   WITH_SELENIUM=1
@@ -70,7 +66,6 @@ commands =
   bash {toxinidir}/tools/selenium_tests.sh {toxinidir} {posargs}
 
 [testenv:selenium-headless]
-envdir = {toxworkdir}/venv
 setenv =
   {[testenv]setenv}
   SELENIUM_HEADLESS=1
@@ -80,7 +75,6 @@ commands =
   bash {toxinidir}/tools/selenium_tests.sh {toxinidir} {posargs}
 
 [testenv:selenium-phantomjs]
-envdir = {toxworkdir}/venv
 setenv =
   {[testenv]setenv}
   SELENIUM_PHANTOMJS=1
@@ -90,7 +84,6 @@ commands =
   bash {toxinidir}/tools/selenium_tests.sh {toxinidir} {posargs}
 
 [testenv:integration]
-envdir = {toxworkdir}/venv
 # Run integration tests only
 passenv =
   DISPLAY
@@ -103,7 +96,6 @@ commands =
   pytest --ds=openstack_dashboard.test.settings -v -x --junitxml="{toxinidir}/test_reports/integration_test_results.xml" --html="{toxinidir}/test_reports/integration_test_results.html" --self-contained-html {posargs:{toxinidir}/openstack_dashboard/test/integration_tests}
 
 [testenv:integration-pytest]
-envdir = {toxworkdir}/venv
 # Run pytest integration tests only
 passenv =
   DISPLAY
@@ -115,7 +107,6 @@ commands =
   pytest -v --junitxml="{toxinidir}/test_reports/integration_pytest_results.xml" --html="{toxinidir}/test_reports/integration_pytest_results.html" --self-contained-html {posargs:{toxinidir}/openstack_dashboard/test/selenium/integration}
 
 [testenv:ui-pytest]
-envdir = {toxworkdir}/venv
 # Run pytest ui tests only
 passenv =
   DISPLAY
@@ -164,7 +155,6 @@ commands =
   doc8 doc/source
 
 [testenv:pdf-docs]
-envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 allowlist_externals =
   make
@@ -173,35 +163,29 @@ commands =
   make -C doc/build/pdf
 
 [testenv:releasenotes]
-envdir = {toxworkdir}/docs
 deps = {[testenv:docs]deps}
 commands =
   sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
   doc8 doc/source
 
 [testenv:manage]
-envdir = {toxworkdir}/venv
 commands = {envpython} {toxinidir}/manage.py {posargs}
 
 [testenv:runserver]
-envdir = {toxworkdir}/venv
 commands =
     {envpython} {toxinidir}/manage.py collectstatic -v 0 -c --noinput
     {envpython} {toxinidir}/manage.py runserver -v 0 {posargs}
 
 [testenv:translations]
-envdir = {toxworkdir}/venv
 commands =
     {envpython} {toxinidir}/manage.py extract_messages -v 0 --traceback
     {envpython} {toxinidir}/manage.py compilemessages -v 0 --traceback
 
 [testenv:bandit]
-envdir = {toxworkdir}/linters
 deps = {[testenv:pep8]deps}
 commands = bandit -r horizon openstack_auth openstack_dashboard -n5 -x tests -ll
 
 [testenv:bandit-baseline]
-envdir = {toxworkdir}/linters
 deps = {[testenv:pep8]deps}
 commands = bandit-baseline -r horizon openstack_auth openstack_dashboard -n5 -x tests -ii -ll