Issue 7039 - [XTM Integration] Make parameter naming consistent with the API docs

tests/utils.py

 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-present eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
@@ skipping 135 matching lines @@
 
 
 class XtmMockArgs:
     """Mock arguments for the XTM integration script."""
 
     class CreationArgsNamespace:
         """Mock arguments for creating a new XTM project."""
 
         name = 'bar'
         desc = 'foo'
-        client_id = 10
+        customer_id = 10
         ref_id = 'faz'
         workflow_id = 20
         save_id = False
         source_dir = None
         projects_func = staticmethod(create_project)
         source_lang = 'en_US'
         workflow_name = None
 
     class UploadArgsNamespace:
         """Mock arguments for uploading files to XTM for translation."""
 
         source_dir = None
         projects_func = staticmethod(upload_files)
         no_overwrite = False
 
     class DownloadArgsNamespace:
         """Mock arguments for downloading translation from XTM."""
 
         source_dir = None
         projects_func = staticmethod(download_files)