Skip brittle HTML editor lettuce test

See [this recent jenkins run](https://jenkins.testeng.edx.org/job/edx-all-tests-auto-pr/10650/SHARD=2,TEST_SUITE=cms-acceptance/testReport/junit/CMS/HTML%20Editor%20_%20Can%20switch%20from%20Raw%20Editor%20to%20Visual/And_I_edit_the_component_and_select_the_Visual_Editor/) for an example intermittent failure.

To fix these tests:

* Don't use world.browser.select, but instead use our wrapped methods, e.g. css_click
* In cms/djangoapps/contentstore/features/component_settings_editor_helpers.py, wait for ajax to finish rendering in edit_component_and_select_settings or maybe it should be in ensure_settings_visible

@cahrens @zubair-arbi