test: #3620843 Use the default view mode page in the Field UI tests

Kasper Garnæsrequested to merge
issue/poll-3620843:3620843-field-ui-tests into 2.0.x

Since Drupal 11.3 the "Manage display" tab opens an overview of the display modes (https://www.drupal.org/node/3574383). The field table now lives on the default view mode page, which also exists on older versions of Drupal Core. PollFieldUITest and PollFieldTest looked for fields on the overview and failed.

Closes #3620843

Merge request reports