refactor(*): Update hard-code '[__HIDDEN__]' to the constant. (#7048)

api/constants/__init__.py

-# TODO: Update all string in code to use this constant
-HIDDEN_VALUE = '[__HIDDEN__]'
+HIDDEN_VALUE = '[__HIDDEN__]'

api/controllers/console/extension.py

 from flask_login import current_user
 from flask_restful import Resource, marshal_with, reqparse
 
+from constants import HIDDEN_VALUE
 from controllers.console import api
 from controllers.console.setup import setup_required
 from controllers.console.wraps import account_initialization_required
         extension_data_from_db.name = args['name']
         extension_data_from_db.api_endpoint = args['api_endpoint']
 
-        if args['api_key'] != '[__HIDDEN__]':
+        if args['api_key'] != HIDDEN_VALUE:
             extension_data_from_db.api_key = args['api_key']
 
         return APIBasedExtensionService.save(extension_data_from_db)

api/core/entities/provider_configuration.py

 
 from pydantic import BaseModel, ConfigDict
 
+from constants import HIDDEN_VALUE
 from core.entities.model_entities import ModelStatus, ModelWithProviderEntity, SimpleModelProviderEntity
 from core.entities.provider_entities import (
     CustomConfiguration,
             for key, value in credentials.items():
                 if key in provider_credential_secret_variables:
                     # if send [__HIDDEN__] in secret input, it will be same as original value
-                    if value == '[__HIDDEN__]' and key in original_credentials:
+                    if value == HIDDEN_VALUE and key in original_credentials:
                         credentials[key] = encrypter.decrypt_token(self.tenant_id, original_credentials[key])
 
         credentials = model_provider_factory.provider_credentials_validate(
             for key, value in credentials.items():
                 if key in provider_credential_secret_variables:
                     # if send [__HIDDEN__] in secret input, it will be same as original value
-                    if value == '[__HIDDEN__]' and key in original_credentials:
+                    if value == HIDDEN_VALUE and key in original_credentials:
                         credentials[key] = encrypter.decrypt_token(self.tenant_id, original_credentials[key])
 
         credentials = model_provider_factory.model_credentials_validate(

api/services/model_load_balancing_service.py

 from json import JSONDecodeError
 from typing import Optional
 
+from constants import HIDDEN_VALUE
 from core.entities.provider_configuration import ProviderConfiguration
 from core.helper import encrypter
 from core.helper.model_provider_cache import ProviderCredentialsCache, ProviderCredentialsCacheType
             for key, value in credentials.items():
                 if key in provider_credential_secret_variables:
                     # if send [__HIDDEN__] in secret input, it will be same as original value
-                    if value == '[__HIDDEN__]' and key in original_credentials:
+                    if value == HIDDEN_VALUE and key in original_credentials:
                         credentials[key] = encrypter.decrypt_token(tenant_id, original_credentials[key])
 
         if validate: