Remove Obsolete QCAlgorithm.OnEndOfDay() (#5441)

* Remove and replace OnEndOfDay() ref

* Restore functionality of obsolete EOD, waiting for deprecation in August 2021

* Cleanup

* Adjustments to only post message when using obsolete EOD

* nit, extra space

* Address review

* Adjust test to reflect new behaviour

* Move GetPythonArgCount to an extension method

* Add unit test

* nit accidental import

* Refactor broken test

* Use Py.GIL() state for extension

Algorithm.Python/RegressionChannelAlgorithm.py

@@ -64,7 +64,7 @@ class RegressionChannelAlgorithm(QCAlgorithm):
             self.SetHoldings(self._spy, -1)
             self.Plot("Trade Plot", "Sell", value)
 
-    def OnEndOfDay(self):
+    def OnEndOfDay(self, symbol):
         self.Plot("Trade Plot", "UpperChannel", self._rc.UpperChannel.Current.Value)
         self.Plot("Trade Plot", "LowerChannel", self._rc.LowerChannel.Current.Value)
         self.Plot("Trade Plot", "Regression", self._rc.LinearRegression.Current.Value)