Ignore pytest-cover warning

Coverage job fails due to to unrelated to our code deprecation warning.
We can not put this warning into ignore list and enable coverage job at
the same commit as our coverage script runs coverage on the prior commit
(i.e. commit that does not have a fix), so we need to merge this change
first and than re-enable coverage job (there is already follow-up change).

Unfortunately, we need to disable rally-tox-pep8 temporary since it is
broken :( The follow-up fix for it is also on the way.

Change-Id: I1ff709a78f7b545823606da2d2b20729e9eeee40

.zuul.d/zuul.yaml

@@ -2,7 +2,7 @@
     check:
       jobs:
         #- rally-tox-cover
-        - rally-tox-pep8
+        #- rally-tox-pep8
         - rally-tox-py36
         - rally-tox-py37
         - rally-tox-py38
@@ -84,7 +84,7 @@
     gate:
       jobs:
         #- rally-tox-cover
-        - rally-tox-pep8
+        #- rally-tox-pep8
         - rally-tox-py36
         - rally-tox-py37
         - rally-tox-py38

tox.ini

@@ -144,3 +144,5 @@ filterwarnings =
     # should be fixed at rally framework (raised by functional job)
     ignore:.*EngineFacade is deprecated; please use oslo_db.sqlalchemy.enginefacade*:
     ignore:.*unclosed file <_io.TextIOWrapper name='/tmp/rally.log'::
+    # pytest-cov
+    ignore:The --rsyncdir command line argument and rsyncdirs config variable are deprecated.:DeprecationWarning: