Make OVS container build regex independent to OVN

Currently building OVN container images and OVS container images are
mutually exclusive.

This becomes problem when all container images are needed to be built
at the same time.

``kolla_build_neutron_ovs`` is added to let user to build OVS even if
OVN is enabled when it's explictly set to true.

Default value ensures regex mapping behaves normally when
``kolla_build_neutron_ovs`` is not given.

Release note is also added.

Change-Id: I7efe883fce4117a5167b6db4a711004d77a44f81

ansible/inventory/group_vars/all/kolla

@@ -202,7 +202,7 @@ overcloud_container_image_regex_map:
   - regex: "neutron-\\(server\\|metadata-agent\\)"
     enabled: "{{ kolla_enable_neutron | bool }}"
   - regex: "neutron-\\(dhcp\\|l3\\|linuxbridge\\|openvswitch\\)-agent"
-    enabled: "{{ kolla_enable_neutron | bool and not kolla_enable_ovn | bool}}"
+    enabled: "{{ kolla_build_neutron_ovs | default(kolla_enable_neutron | bool and not kolla_enable_ovn | bool) }}"
   - regex: neutron-mlnx-agent
     enabled: "{{ kolla_enable_neutron_mlnx | bool }}"
   - regex: neutron-ovn-agent

doc/source/deployment.rst

@@ -533,6 +533,12 @@ image name regular expressions::
 
     (kayobe) $ kayobe overcloud container image build ironic- nova-api
 
+When your environment uses OVN, OVS images will not be built. If you want to
+build all Neutron images at the same time, extra variable ``kolla_build_neutron_ovs``
+needs to be set to ``true``::
+
+    (kayobe) $ kayobe overcloud container image build -e kolla_build_neutron_ovs=true
+
 In order to push images to a registry after they are built, add the ``--push``
 argument.
 

releasenotes/notes/add_option_to_build_OVS_images_while_using_OVN-48471bbaebc953be.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Adds a new variable ``kolla_build_neutron_ovs`` which gives users to have
+    option to build OVS container images while the system is using OVN.
+    This is useful when an user wants to build all container images at the
+    same time.