Revert "Add new attribute for system_dbus_client, that will allow unconfined_service_t to dbus chat with all dbus domains"

This reverts commit 547e6efae4a47d982e0041c8c3974f9ef48937b0.

This concept does not work because of attributes.

"typeattribute system_bus_type system_bus_client;"

and others because we call it for attributes.