Improve test reliability by resetting parameters for test_todo_list_api tests

[sturmianseq]

This PR aims to improve the reliability of tests tests/test_view_boosters/test_todo_list_api/test_api_endpoints.py::test_multi_users_creation, tests/test_view_boosters/test_todo_list_api/test_api_endpoints.py::test_user_creation and tests/test_view_boosters/test_todo_list_api/test_relationship_updates.py::test_list_relationship_new_item by cleaning the state before running it.

The test can fail on the second run by running it twice. For example, you can run pip3 install pytest-repeat; python3 -m pytest --count=2 tests/test_view_boosters/test_todo_list_api/test_api_endpoints.py::test_multi_users_creation to get the following failure:

...
    def do_execute(self, cursor, statement, parameters, context=None):
>       cursor.execute(statement, parameters)
E       sqlite3.IntegrityError: UNIQUE constraint failed: user.email
...
==================== 1 failed, 1 passed, 1 warning in 0.88s ====================

More specifically, this PR initializes the parameters for each unit test. In this way, the tests do not fail on the second run any more. It may be better to avoid the state pollutions so that some other tests won't fail in the future due to the shared state pollution.