daemon: Remove connection socket properly
The naming scheme for the non-abstract socket was changed but
new_connection_data_free
was not adjusted to match.
GDBusServer
will remove the socket when it stops, but only if
g_dbus_server_start
was called. So we can simplify the process
somewhat. Also don't bother removing the directory now that all sockets
share it.
Relates: #515 (closed)
Edited by Jan Alexander Steffens