Get rid of timer_actions hook

Nothing uses it.  In the unlikely event we need it back, we
should call it qt_timer_actions instead as it is QT-only and
runs in the QT GUI thread.

gui/qt/main_window.py

@@ -507,7 +507,6 @@ class ElectrumWindow(QMainWindow, MessageBoxMixin, PrintError):
         if self.require_fee_update:
             self.do_update_fee()
             self.require_fee_update = False
-        run_hook('timer_actions')
 
     def format_amount(self, x, is_diff=False, whitespaces=False):
         return format_satoshis(x, is_diff, self.num_zeros, self.decimal_point, whitespaces)