Pin neutron-tempest-plugin for stable/wallaby jobs

As stable/wallaby is in EM phase, and currently broken
with the Tempest master. We are pinning tempest there (depends-on).

We are using the tempest 29.0.0 on stable/wallaby (depends-on) and
compatible tag for tempest 29.0.0 is neutron-tempest-plugin 1.8.0
(as neutron-tempest-plugin >= 1.9.0 need tempest>-29.2.0) 

- https://github.com/openstack/neutron-tempest-plugin/blob/1.9.0/requirements.txt#L14
- https://zuul.opendev.org/t/openstack/build/f644e4c4c2234ba981c56d91a5b11cbf

As stable/wallaby is in EM phase, we can remove the wallaby job
from master gate.

Depends-On: https://review.opendev.org/c/openstack/devstack/+/871782
Change-Id: Ide5789b40180d572459d47dbd474433644e4dcd7
diff --git a/zuul.d/base-nested-switch.yaml b/zuul.d/base-nested-switch.yaml
index 9689d82..f92b08b 100644
--- a/zuul.d/base-nested-switch.yaml
+++ b/zuul.d/base-nested-switch.yaml
@@ -13,7 +13,7 @@
     name: neutron-tempest-plugin-base-nested-switch
     parent: neutron-tempest-plugin-base
     abstract: true
-    branches: ^(?!stable/(queens|rocky|stein|train|ussuri|victoria)).*$
+    branches: ^(?!stable/(queens|rocky|stein|train|ussuri|victoria|wallaby)).*$
     # Comment nodeset and vars to switch back to non nested nodes
     nodeset: neutron-nested-virt-ubuntu-focal
     vars:
@@ -29,4 +29,4 @@
     name: neutron-tempest-plugin-base-nested-switch
     parent: neutron-tempest-plugin-base
     abstract: true
-    branches: ^(stable/(queens|rocky|stein|train|ussuri|victoria)).*$
+    branches: ^(stable/(queens|rocky|stein|train|ussuri|victoria|wallaby)).*$