status/network: Only show custom wired names

status/network: Only show custom wired names

Thanks to NetworkManager's connection name disambiguation, it's
pretty common for single wired connections to be named "Wired". This
is fine and what we want almost all times, but in the specific case
of quick settings, we already have a "Wired" string set as title of
the quick settings toggle, so having that as subtitle is reduntant.

Hide the subtitle label (by returning null) when the subtitle of
a wired network matches the title.

Fixes ab10b95d2dc6bda1fc0fcc3b451e535f2fc160a8
Closes https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6369

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2627>