Drop environments for nose

Horizon dropped its usage of nose in 14.0.0[1] and these environments
have been unused since then.

[1] 1f80d94459856a8c477310cc0fe4b0e165d8c0c1

Also remove a few leftovers from old versions.

Change-Id: I8a0113a94fe07bdc49f47feefcf9dfa846948259

tox.ini

@@ -1,16 +1,11 @@
 [tox]
-envlist = pep8,eslint,karma-local,docs-local,releasenotes,lower-constraints-local
+envlist = pep8,eslint,karma-local,docs-local,releasenotes
 minversion = 3.18.0
 
 [testenv]
 usedevelop = True
-setenv = VIRTUAL_ENV={envdir}
-         NOSE_WITH_OPENSTACK=1
-         NOSE_OPENSTACK_COLOR=1
-         NOSE_OPENSTACK_RED=0.05
-         NOSE_OPENSTACK_YELLOW=0.025
-         NOSE_OPENSTACK_SHOW_ELAPSED=1
-         DJANGO_SETTINGS_MODULE=zaqar_ui.test.settings
+setenv =
+  DJANGO_SETTINGS_MODULE=zaqar_ui.test.settings
 deps =
   -c{env:TOX_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
   -r{toxinidir}/requirements.txt
@@ -35,7 +30,6 @@ ignore = F405,W504
 exclude = .venv,.git,.tox,dist,*lib/python*,*egg,build,panel_template,dash_template,local_settings.py,*/local/*,*/test/test_plugins/*,.ropeproject,node_modules
 max-complexity = 20
 
-
 [testenv:cover]
 commands =
   coverage erase
@@ -46,8 +40,7 @@ commands =
 # NOTE(shu-mutow): On CI infra, horizon will be installed
 # according to job setting. but on local, we need to install
 # horizon from master branch.
-[testenv:py36-local]
-basepython = python3.6
+[testenv:py3-local]
 commands =
   {[testenv:hz-local]commands}
   {[testenv]commands}