[python] Some cleanup of samples folder (#17127)

* Delete sample folders of discontinued clients

* Remove duplicate python-flask server sample

The python-flask sample actually lives in samples/server/petstore/python-flask.

* Move hand-written test to "tests" folder

Now, "test" only contains generated stubs and all hand-written tests are in "tests".

* Delete left-over files in Python samples

These are not created by the generators (anymore) and not hand-written
for testing.

* Regenerate test file to fix import error

samples/openapi3/client/petstore/python/tests/test_configuration.py

@@ -19,7 +19,7 @@ class TestConfiguration(unittest.TestCase):
     """Animal unit test stubs"""
 
     def setUp(self):
-        pass
+        self.config = petstore_api.Configuration()
 
     def tearDown(self):
         # reset Configuration
@@ -58,5 +58,23 @@ class TestConfiguration(unittest.TestCase):
         c1 = petstore_api.Configuration(access_token="12345")
         self.assertEqual(c1.access_token, "12345")
 
+    def test_get_host_settings(self):
+        host_settings = self.config.get_host_settings()
+
+        self.assertEqual('http://{server}.swagger.io:{port}/v2', host_settings[0]['url'])
+        self.assertEqual('petstore', host_settings[0]['variables']['server']['default_value'])
+
+        self.assertEqual('https://localhost:8080/{version}', host_settings[1]['url'])
+        self.assertEqual('v2', host_settings[1]['variables']['version']['default_value'])
+
+    def test_get_host_from_settings(self):
+        """ Test get_host_from_settings
+
+        Test get URL from host settings
+        """
+        self.assertEqual("http://petstore.swagger.io:80/v2", self.config.get_host_from_settings(0))
+        self.assertEqual("http://petstore.swagger.io:8080/v2", self.config.get_host_from_settings(0, {'port': '8080'}))
+        self.assertEqual("http://dev-petstore.swagger.io:8080/v2", self.config.get_host_from_settings(0, {'server': 'dev-petstore', 'port': '8080'}))
+
 if __name__ == '__main__':
     unittest.main()