Temporarily set octavia-v2-dsvm-py2-scenario non-voting

A recent change lowered the swap space on nodepool instances to 1 GB
[1]. Octavia scenario jobs were impacted, particularly Python 2 jobs
to the point -py2 job builds constantly fail.

To unlock stable/train and stable/stein gates, we need to temporarily
set octavia-v2-dsvm-py2-scenario non-voting. This change will be
reverted as soon as [2] and [3] merge.

[1] https://review.opendev.org/#/c/750941/
[2] https://review.opendev.org/#/c/755777
[3] https://review.opendev.org/#/c/757841/

Change-Id: Ifc53049e7135e2623bcf7bc2287262ba2f70382d

zuul.d/projects.yaml

@@ -30,7 +30,8 @@
         - octavia-v2-dsvm-noop-api
         - octavia-v2-dsvm-noop-py2-api
         - octavia-v2-dsvm-scenario
-        - octavia-v2-dsvm-py2-scenario
+        - octavia-v2-dsvm-py2-scenario:
+            voting: false
         - octavia-v2-dsvm-py2-scenario-centos-7:
             voting: false
         - octavia-v2-dsvm-scenario-two-node:
@@ -91,7 +92,6 @@
         - octavia-v2-dsvm-noop-api
         - octavia-v2-dsvm-noop-py2-api
         - octavia-v2-dsvm-scenario
-        - octavia-v2-dsvm-py2-scenario
         - octavia-grenade:
             irrelevant-files:
               - ^.*\.rst$