Disable pyXY tests on internal CI

this repo has no actual unit tests and when executing test runner
attempts to run actual tempest tests.

The CI job checks the list of default envs before runnning given
tox env. While this is actually wrong (those pyXY envs are
actually auto-generated by tox), removing them from default env
list unblocks our internal CI.

Related-prod: PROD-22634

Change-Id: I5adcf91bd21f6654c86155d9097c29d357468c8c
(cherry picked from commit 4352bcce16b223632292c55113f2691924fc984c)
(cherry picked from commit 5908bf3d7bdda85c3709f6c91a57153af565d345)
diff --git a/tox.ini b/tox.ini
index 47d4fa6..c53c2e2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,6 @@
 [tox]
 minversion = 1.6
-envlist = py34,py27,pypy,pep8
+envlist = pep8
 skipsdist = True
 
 [testenv]