Revert "Fix circular references"
Reverts taurus-org/taurus#682 cause it breaks the expected behavior of BoundMethodWeakref
class.
Sardana uses the BoundMethodWeakref.__call__
in order to retrieve the reference to the method in: https://github.com/sardana-org/sardana/blob/82e1402b648dde4eafc44a8412778bf7dd8b8359/src/sardana/sardanaevent.py#L123
for further method invocation with the real arguments.