ovn: Do not schedule SNAT routers on computes

Currently we set enable-chassis-as-gw on compute nodes when distributed FIP
is enabled - that is not required for FIP functionality.

Change-Id: Ic880a9479fa0cdbb1d1cae3dbe9523ef2e1132ce
Closes-Bug: #1901960
(cherry picked from commit 06baf51)

Author: mnasiadka

ansible/roles/ovn/tasks/bootstrap.yml

@@ -27,9 +27,12 @@
 - name: Enable chassis as gateway
   become: true
   command: docker exec openvswitch_vswitchd ovs-vsctl set Open_vSwitch . external-ids:ovn-cms-options="enable-chassis-as-gw"
-  when:
-    - inventory_hostname in groups["ovn-controller-network"]
-      or (inventory_hostname in groups["ovn-controller-compute"] and neutron_ovn_distributed_fip | bool)
+  when: inventory_hostname in groups["ovn-controller-network"]
+
+- name: Ensure chassis as gateway is disabled where required
+  become: true
+  command: docker exec openvswitch_vswitchd ovs-vsctl remove Open_vSwitch . external-ids ovn-cms-options
+  when: inventory_hostname not in groups["ovn-controller-network"]
 
 - name: Set OVN remote probe interval
   become: true

releasenotes/notes/bug-1901960-363503e11449b53c.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    OVN will no longer schedule SNAT routers on compute nodes
+    when ``neutron_ovn_distributed_fip`` is enabled.
+    `LP#1901960 <https://launchpad.net/bugs/1901960>`__