Follow-up to MGNLTEST-267.
Some POs have already been rewritten.

Workarounds for Selenium quirks we had to introduce ourselves (WebElement wrapping comes to mind, for instance, but there are others) can likely be removed in the process.

This migration will be executed gradually.  We should integrate to master main  not all the changes in one commit - instead adding each result of subtasks individually - one by one.