Move to debhelper compat level 10

- No need to depend on dh-systemd explicitly, it is now the default
- No need to enable dh-autoreconf explicitly or depend on it, it is
  now the default

Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Reviewed-by: Justin Kim <justin.kim@collabora.com>
Differential Revision: https://phabricator.apertis.org/D5486