Remove callspec related block of code

It seems this is no longer required now that we don't support
yield tests anymore. The param attribute was added here:

https://github.com/pytest-dev/pytest/blob/91b6f2bda8668e0f74190ed223a9eec01d09a0a7/_pytest/python.py#L888-L891

src/_pytest/python.py

@@ -1414,11 +1414,6 @@ class Function(FunctionMixin, nodes.Item, fixtures.FuncargnamesCompatAttr):
 
     def _initrequest(self):
         self.funcargs = {}
-        if hasattr(self, "callspec"):
-            callspec = self.callspec
-            assert not callspec.funcargs
-            if hasattr(callspec, "param"):
-                self.param = callspec.param
         self._request = fixtures.FixtureRequest(self)
 
     @property