[python][client] Clean up samples and CI (#17509)

* chore: Remove leftover Github action file

This was probably added by mistake. A similar file is active in
.github/workflows/samples-python-pydantic-v1-petstore.yaml.

* chore: Remove leftover VERSION from old python-experimental sample

* ci: Stop running Python integration tests in Circle CI

These Python clients are all tested with Github Actions already, which
is faster, more cleanly separated and only runs on modifications.

I'm not cleaning up the pydantic-v1 client, I expect it to be removed soon anyway.

* chore: Remove true from sample folder name

python-disallowAdditionalPropertiesIfNotPresent-true
-> python-disallowAdditionalPropertiesIfNotPresent

samples/client/echo_api/python-disallowAdditionalPropertiesIfNotPresent/docs/HeaderApi.md

@@ -0,0 +1,85 @@
+# openapi_client.HeaderApi
+
+All URIs are relative to *http://localhost:3000*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**test_header_integer_boolean_string_enums**](HeaderApi.md#test_header_integer_boolean_string_enums) | **GET** /header/integer/boolean/string/enums | Test header parameter(s)
+
+
+# **test_header_integer_boolean_string_enums**
+> str test_header_integer_boolean_string_enums(integer_header=integer_header, boolean_header=boolean_header, string_header=string_header, enum_nonref_string_header=enum_nonref_string_header, enum_ref_string_header=enum_ref_string_header)
+
+Test header parameter(s)
+
+Test header parameter(s)
+
+### Example
+
+
+```python
+import openapi_client
+from openapi_client.models.string_enum_ref import StringEnumRef
+from openapi_client.rest import ApiException
+from pprint import pprint
+
+# Defining the host is optional and defaults to http://localhost:3000
+# See configuration.py for a list of all supported configuration parameters.
+configuration = openapi_client.Configuration(
+    host = "http://localhost:3000"
+)
+
+
+# Enter a context with an instance of the API client
+with openapi_client.ApiClient(configuration) as api_client:
+    # Create an instance of the API class
+    api_instance = openapi_client.HeaderApi(api_client)
+    integer_header = 56 # int |  (optional)
+    boolean_header = True # bool |  (optional)
+    string_header = 'string_header_example' # str |  (optional)
+    enum_nonref_string_header = 'enum_nonref_string_header_example' # str |  (optional)
+    enum_ref_string_header = openapi_client.StringEnumRef() # StringEnumRef |  (optional)
+
+    try:
+        # Test header parameter(s)
+        api_response = api_instance.test_header_integer_boolean_string_enums(integer_header=integer_header, boolean_header=boolean_header, string_header=string_header, enum_nonref_string_header=enum_nonref_string_header, enum_ref_string_header=enum_ref_string_header)
+        print("The response of HeaderApi->test_header_integer_boolean_string_enums:\n")
+        pprint(api_response)
+    except Exception as e:
+        print("Exception when calling HeaderApi->test_header_integer_boolean_string_enums: %s\n" % e)
+```
+
+
+
+### Parameters
+
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **integer_header** | **int**|  | [optional] 
+ **boolean_header** | **bool**|  | [optional] 
+ **string_header** | **str**|  | [optional] 
+ **enum_nonref_string_header** | **str**|  | [optional] 
+ **enum_ref_string_header** | [**StringEnumRef**](.md)|  | [optional] 
+
+### Return type
+
+**str**
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: text/plain
+
+### HTTP response details
+
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+**200** | Successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+