[unmaintained-only] Use proper versions for grenade

Also pin project specific tempest plugins to <series>-last tags.

Conflicts, changes:
  roles/configure-grenade-branches/defaults/main.yaml
  .zuul.yaml

Conflicts and changes are due to branch names need to be adjusted to
actual branch.

Change-Id: Id8e09096fc4fe6241cb95b7edbd14609667c3e7b
(cherry picked from commit 7da2da2ff5)

.zuul.yaml

@@ -5,16 +5,28 @@
       jobs:
         - grenade
         - grenade-multinode
-        - grenade-heat-multinode
-        - octavia-grenade
+        - grenade-heat-multinode:
+            required-projects:
+              - name: opendev.org/openstack/heat-tempest-plugin
+                override-checkout: zed-last
+        - octavia-grenade:
+            required-projects:
+              - name: opendev.org/openstack/octavia-tempest-plugin
+                override-checkout: zed-last
         - ironic-grenade:
             voting: false
     gate:
       jobs:
         - grenade
         - grenade-multinode
-        - grenade-heat-multinode
-        - octavia-grenade
+        - grenade-heat-multinode:
+            required-projects:
+              - name: opendev.org/openstack/heat-tempest-plugin
+                override-checkout: zed-last
+        - octavia-grenade:
+            required-projects:
+              - name: opendev.org/openstack/octavia-tempest-plugin
+                override-checkout: zed-last
     experimental:
       jobs:
         - grenade-forward

roles/configure-grenade-branches/defaults/main.yaml

@@ -1,3 +1,3 @@
 ---
-grenade_from_branch: stable/yoga
-grenade_to_branch: stable/zed
+grenade_from_branch: unmaintained/yoga
+grenade_to_branch: unmaintained/zed