Move devstack-gate jobs list to in-tree

It is easy to know all the jobs running on devstack-gate
if they are listed in-tree.

This will also help in deprecation of devstack-gate for master
(Xena onwards) while converting those jobs to run for stable branch.

Depends-On: https://review.opendev.org/c/openstack/project-config/+/795379

Change-Id: Id5262a22fb119447eecb0a77f1d2be2940786226

.zuul.yaml

@@ -23,10 +23,25 @@
       - openstack/tempest
 
 - project:
+    templates:
+      - integrated-gate-py3
+      - official-openstack-repo-jobs
+      - openstack-python35-jobs
     check:
       jobs:
         - openstack-tox-bashate:
             nodeset: ubuntu-bionic
+        - openstack-tox-py27
+        - neutron-grenade
+        - neutron-grenade-multinode
+        - neutron-grenade-dvr-multinode:
+            voting: false
+        - legacy-tempest-dsvm-neutron-full-ocata:
+            voting: false
+        - legacy-tempest-dsvm-neutron-full-centos-7:
+            voting: false
+        - legacy-tempest-dsvm-multinode-full:
+            voting: false
         - devstack:
             files:
               - ^roles/
@@ -36,3 +51,13 @@
             branches: ^(?!driverfixes/).*$
             voting: false
         - devstack-gate-hooks
+    gate:
+      queue: integrated
+      jobs:
+        - openstack-tox-py27
+        - neutron-grenade
+        - neutron-grenade-multinode
+    experimental:
+      jobs:
+        - legacy-tempest-dsvm-neutron-dvr-multinode-full
+        - neutron-tempest-dvr-ha-multinode-full