Now that we are logging `flatpak -v` messages with log level INFO,
and printing INFO messages in the same way as DEBUG, we can reserve
log level DEBUG for `flatpak -v -v` messages. This means we no longer
need a weird secondary debug domain.
There is a very small behaviour change here: G_MESSAGES_DEBUG=flatpak
is now similar to `flatpak -v -v` (previously `flatpak -v`), and
G_MESSAGES_DEBUG=flatpak2 no longer has any effect. This seems more in
line with what would be expected from a GLib-based application.
In flatpak(1) and the system helper, this does not change behaviour
other than that: the same messages are logged by `-v` and by `-v -v`
as before.
In daemons that do not implement `-v -v` (the OCI authenticator, portal
and session helper), it continues to be necessary to use
G_MESSAGES_DEBUG to see flatpak_debug2() messages.
Signed-off-by: Simon McVittie <smcv@collabora.com>