find_elements_by_xpath: use a modified call to `page.all` instead of the undocumented `page.document.find_xpath`
find_elements_by_xpath: use a modified call to `page.all` instead of the undocumented `page.document.find_xpath`

also insert miniscule wait time to allow our synchronize_with_unload_wait
mechanism to be engaged but not slow down the test significantly

alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests,alphagov/digitalmarketplace-functional-tests