Remove the Ocata stable branch jobs from master gate

Tempest 20.0.0 is released now, which marks the end of support
for Ocata release - https://review.openstack.org/#/c/645867/

We do not need to run the Ocata stable job om master gate now.
Depends-On: https://review.openstack.org/#/c/645867

Change-Id: I883f3c98201631acdadeaab6678a796a85662e44
diff --git a/.zuul.yaml b/.zuul.yaml
index 71bbeca..7197c3a 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -569,8 +569,6 @@
             irrelevant-files: *tempest-irrelevant-files
         - neutron-tempest-dvr:
             irrelevant-files: *tempest-irrelevant-files
-        - legacy-tempest-dsvm-neutron-full-ocata:
-            irrelevant-files: *tempest-irrelevant-files
         - tempest-full:
             irrelevant-files: *tempest-irrelevant-files
         - interop-tempest-consistency: