[Python] remove default value from being fallback to example (#2213)

* remove example fallback

* reset test case

samples/client/petstore/python/docs/Pet.md

@@ -5,7 +5,7 @@ Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
 **id** | **int** |  | [optional] 
 **category** | [**Category**](Category.md) |  | [optional] 
-**name** | **str** |  | [default to 'doggie']
+**name** | **str** |  | 
 **photo_urls** | **list[str]** |  | 
 **tags** | [**list[Tag]**](Tag.md) |  | [optional] 
 **status** | **str** | pet status in the store | [optional] 

samples/client/petstore/python/docs/TypeHolderExample.md

@@ -3,11 +3,11 @@
 ## Properties
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
-**string_item** | **str** |  | [default to 'what']
+**string_item** | **str** |  | 
 **number_item** | **float** |  | [default to 1.234]
-**integer_item** | **int** |  | [default to -2]
-**bool_item** | **bool** |  | [default to True]
-**array_item** | **list[int]** |  | [default to [0, 1, 2, 3]]
+**integer_item** | **int** |  | 
+**bool_item** | **bool** |  | 
+**array_item** | **list[int]** |  | 
 
 [[Back to Model list]](../README.md#documentation-for-models) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to README]](../README.md)
 

samples/client/petstore/python/docs/XmlItem.md

@@ -3,33 +3,33 @@
 ## Properties
 Name | Type | Description | Notes
 ------------ | ------------- | ------------- | -------------
-**attribute_string** | **str** |  | [optional] [default to 'string']
+**attribute_string** | **str** |  | [optional] 
 **attribute_number** | **float** |  | [optional] [default to 1.234]
-**attribute_integer** | **int** |  | [optional] [default to -2]
-**attribute_boolean** | **bool** |  | [optional] [default to True]
+**attribute_integer** | **int** |  | [optional] 
+**attribute_boolean** | **bool** |  | [optional] 
 **wrapped_array** | **list[int]** |  | [optional] 
-**name_string** | **str** |  | [optional] [default to 'string']
+**name_string** | **str** |  | [optional] 
 **name_number** | **float** |  | [optional] [default to 1.234]
-**name_integer** | **int** |  | [optional] [default to -2]
-**name_boolean** | **bool** |  | [optional] [default to True]
+**name_integer** | **int** |  | [optional] 
+**name_boolean** | **bool** |  | [optional] 
 **name_array** | **list[int]** |  | [optional] 
 **name_wrapped_array** | **list[int]** |  | [optional] 
-**prefix_string** | **str** |  | [optional] [default to 'string']
+**prefix_string** | **str** |  | [optional] 
 **prefix_number** | **float** |  | [optional] [default to 1.234]
-**prefix_integer** | **int** |  | [optional] [default to -2]
-**prefix_boolean** | **bool** |  | [optional] [default to True]
+**prefix_integer** | **int** |  | [optional] 
+**prefix_boolean** | **bool** |  | [optional] 
 **prefix_array** | **list[int]** |  | [optional] 
 **prefix_wrapped_array** | **list[int]** |  | [optional] 
-**namespace_string** | **str** |  | [optional] [default to 'string']
+**namespace_string** | **str** |  | [optional] 
 **namespace_number** | **float** |  | [optional] [default to 1.234]
-**namespace_integer** | **int** |  | [optional] [default to -2]
-**namespace_boolean** | **bool** |  | [optional] [default to True]
+**namespace_integer** | **int** |  | [optional] 
+**namespace_boolean** | **bool** |  | [optional] 
 **namespace_array** | **list[int]** |  | [optional] 
 **namespace_wrapped_array** | **list[int]** |  | [optional] 
-**prefix_ns_string** | **str** |  | [optional] [default to 'string']
+**prefix_ns_string** | **str** |  | [optional] 
 **prefix_ns_number** | **float** |  | [optional] [default to 1.234]
-**prefix_ns_integer** | **int** |  | [optional] [default to -2]
-**prefix_ns_boolean** | **bool** |  | [optional] [default to True]
+**prefix_ns_integer** | **int** |  | [optional] 
+**prefix_ns_boolean** | **bool** |  | [optional] 
 **prefix_ns_array** | **list[int]** |  | [optional] 
 **prefix_ns_wrapped_array** | **list[int]** |  | [optional]