improved capybara select2 helpers

Existing `select2` used `sleep(1)` to wait for the select2 dropdown to appear and then executed some javascript to select the desired option. This replaces that with a standard capybara `page.find(...).click`.

As well with avoiding the `sleep(1)`, this will raise an exception if the desired option is missing.

The build reliably passes on my machine, hopefully CI agrees.