gdbusauthmechanismsha1: Reduce the expiry timeout for old keys to 7 mins
This moves it inline with the timeout in libdbus-1, which fixes a
spurious failure of the gdbus-server-auth
test caused by libdbus-1 and
gdbus choosing to expire the key at different times.
Diagnosed by Thiago Macieira.
Signed-off-by: Philip Withnall withnall@endlessm.com
Fixes: #2164 (closed)