The ID_MM_PROCESS tag should be set by the user when using the
allowlist filter, we must not ship any device flagged by default with
that tag.

Moreover, the two ENV actions in a single rule is something not
currently supported by the builtin udev rule parser that is used in
systems without udev (e.g. openwrt).

Fixes https://gitlab.freedesktop.org/mobile-broadband/ModemManager/-/issues/779