text: Title: Do not override user settings when running cloud set-key tests
  Body: Some of the cloud tests call the set-key command to verify the functionality. However, this causes the user's existing key to be overridden after running the tests.
  
  We should add a `pytest.fixture` that backs up the user settings and it restores them after the test runs. Essentially, we need to backup the file that stores the key.
  
  https://github.com/ploomber/ploomber/blob/9e11fcbcdf763d6f3111e8254dc327a56306971e/tests/cli/test_cloud.py#L125