make a seperate file test_users_negative.py and move exist negative tests
over to it,also add some negative tests to it
- test_create_user_with_enabled_non_bool
- test_create_user_with_enabled
- create_user
- test_update_user_for_non_existant_user
- test_update_user_request_without_a_token
- test_update_user_by_unauthorized_user
- test_delete_user_request_without_a_token
Change-Id: I5a87d72ecb94046809faf0ce14b1af347c2e4dcc
fc8db4f6ac