Remove legacy gate jobs

Remove legacy gate jobs from this repo. Initially these will be
replaced by entries in the project-local gate configurtion, and
will eventually be transitioned to non-legacy gate jobs.

Change-Id: Id3f54204996ee3b69cde5dbaa0d14a28f3335a65

zuul.d/projects.yaml

@@ -6992,17 +6992,6 @@
     name: x/group-based-policy
     templates:
       - publish-to-pypi
-    check:
-      jobs:
-        - legacy-group-based-policy-dsvm-functional:
-            voting: false
-            branches: ^(?!stable/mitaka).*$
-        - legacy-group-based-policy-dsvm-aim:
-            voting: false
-            branches: ^(?!stable/mitaka).*$
-        - legacy-group-based-policy-dsvm-nfp:
-            voting: false
-            branches: ^(?!stable/mitaka).*$
 
 - project:
     name: x/group-based-policy-automation