Fix Train neutron-tempest-plugin api job

With [1] IMAGE_URLS and CUSTOMIZE_IMAGE are updated
making api tempest plugin jobs fail in stable branches.
This patch fixing Train job, Ussuri/Victoria being
fixed in [2].

[1] https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/836912
[2] https://review.opendev.org/c/openstack/neutron-tempest-plugin/+/838053

Change-Id: I3affc8c4f3e26db020a10296ee2b805f7280e401
diff --git a/zuul.d/train_jobs.yaml b/zuul.d/train_jobs.yaml
index b6caa11..961b3b7 100644
--- a/zuul.d/train_jobs.yaml
+++ b/zuul.d/train_jobs.yaml
@@ -103,6 +103,12 @@
       network_available_features: &available_features
         -
       devstack_localrc:
+        # NOTE(bcafarel) guestmount binary not available on host OS
+        IMAGE_URLS: https://cloud-images.ubuntu.com/releases/bionic/release/ubuntu-18.04-server-cloudimg-amd64.img
+        ADVANCED_IMAGE_NAME: ubuntu-18.04-server-cloudimg-amd64
+        ADVANCED_INSTANCE_TYPE: ds512M
+        ADVANCED_INSTANCE_USER: ubuntu
+        CUSTOMIZE_IMAGE: false
         NEUTRON_DEPLOY_MOD_WSGI: false
         NETWORK_API_EXTENSIONS: "{{ (network_api_extensions_common + network_api_extensions_tempest) | join(',') }}"
         Q_AGENT: openvswitch