Python-exp clean up model classnames (#7054)

* Adds lazy_import, removes python-exp java class renaming code, partial removal of getPythonClassName call sites

Fixes PythonClientExperimentalTest.java

Python-exp smaples regeneration

Revers makefile

Reverst pom.xml

Fixes model imports in models.__init__

Updates docstring, omits lazy import in additional properties if we dont need it

Improves additional_properties_type assignment if None

Removes getPythonClassName

Fixes python-exp tests

* Removes unused makefiles

samples/openapi3/client/extensions/x-auth-id-alias/python-experimental/x_auth_id_alias/model_utils.py

@@ -41,9 +41,9 @@ class cached_property(object):
         self._fn = fn
 
     def __get__(self, instance, cls=None):
-        try:
+        if self.result_key in vars(self):
             return vars(self)[self.result_key]
-        except KeyError:
+        else:
             result = self._fn()
             setattr(self, self.result_key, result)
             return result