Comment 1 for bug 1956264

According to @rlaager on LP: #1771740 systemd-networkd should be able to handle those settings as a tristate unset/on/off. This needs to be confirmed and if valid, netplan should do the same.

> Upon further investigation, I see that the systemd networkd settings have similar documentation only listing true and unset. But the systemd NEWS file explicitly talks about disabling and the settings are parsed in networkd using config_parse_tristate, so I think networkd properly handles =0 on these options. (I'm still trying to test it.)