circleci: drop libnss-systemd from Ubuntu
circleci: drop libnss-systemd from Ubuntu

This is installed by software-properties-common, but since we don't
start our container with systemd, it effectively points to nowhere, adding
nothing but a delay of several minutes.

That delay affects dbus-daemon on startup and on configuration reload, it
takes several minutes to do either. ratbagctl.test installs a custom dbus
config file to be able to connect to ratbagd.devel, that config file triggers
a reload in the dbus-daemon. Since that reload takes longer than any of our
timeouts, the tests eventually fail.

Signed-off-by: Peter Hutterer <b9c50af7afa7642f6f854434cda9ffe54ece8b85@who-t.net>

whot/libratbag,whot/libratbag,libratbag/libratbag,whot/libratbag,libratbag/libratbag,libratbag/libratbag