Add octavia-v2-dsvm-scenario-centos-8

This patch adds a new non-voting scenario job to test against CentOS 8
amphora images. Until CentOS 8 controllers are supported in Devstack,
this job runs Ubuntu controllers.

Depends-On: https://review.opendev.org/#/c/697128/
Change-Id: Ia5cffced9d5af2de3a85b91be5358a15234f5e25
diff --git a/zuul.d/projects.yaml b/zuul.d/projects.yaml
index 965f961..4445910 100644
--- a/zuul.d/projects.yaml
+++ b/zuul.d/projects.yaml
@@ -20,6 +20,8 @@
         - octavia-v2-dsvm-py2-scenario-stable-queens
         - octavia-v2-dsvm-scenario-ipv6-only:
             voting: false
+        - octavia-v2-dsvm-scenario-centos-8:
+            voting: false
         - octavia-v2-dsvm-scenario-ubuntu-bionic:
             voting: false
         - octavia-v2-act-stdby-dsvm-scenario-two-node: