Temporarily disable sahara-scenario* (train only)

A weird interaction between python3 and virtualenvs created
with system-site-packages breaks the runs of those jobs.

Temporarily disable them to allow other fixes to be merged.

Change-Id: I2740e649520081e6578bb856894c97ee72146fa8
Story: 2008355
Task: 41259

.zuul.yaml

@@ -11,8 +11,10 @@
       jobs:
         - openstack-tox-pylint:
             voting: false
-        - sahara-tests-scenario
-        - sahara-tests-scenario-v2
+        - sahara-tests-scenario:
+            voting: false
+        - sahara-tests-scenario-v2:
+            voting: false
         - sahara-tests-tempest
         - sahara-tests-tempest-v2
         - openstack-tox-cover:
@@ -26,8 +28,8 @@
     gate:
       queue: sahara
       jobs:
-        - sahara-tests-scenario
-        - sahara-tests-scenario-v2
+        # - sahara-tests-scenario
+        # - sahara-tests-scenario-v2
         - sahara-tests-tempest
         - sahara-tests-tempest-v2
         - sahara-grenade