Previously ovn-chassis-mac-mappings [1] has been added only to
ovn-controller-compute group. However external ports are being
scheduled on network nodes, therefore we need also do that there.

Closes-Bug: 1995078

[1] https://github.com/ovn-org/ovn/blob/v22.09.0/controller/ovn-controller.8.xml#L239

Change-Id: Ie62e9220bad56262cad602ca1480e6ca65827819