One can install the libraries without NetworkManager. Thus, the
translations should be there.
Doing this increases the package size of the libraries significantly.
For a user who only has libnm without NetworkManager installed, this
is acceptable, because the whole point of the change is to ensure such
a user also gets translations.
For a user who requires libnm and libnm-glib packages, this
unfortunately increases the additional package size as the translations
are now present twice.
What would be better is if NetworkManager-libnm would only contain
translations for libnm/NetworkManager, and NetworkManager-glib only
translations for libnm-util/libnm-glib.