Drupal 11 compatibility fixes for entity_reference_delete_check

Please take a look at the review and discuss.

Hi @tgauges, thanks for the review.

I've tried to address all the points raised by your code review.

Thank you a lot for your efforts. I think the remaining discussion point is whether Drupal 9 to 10.2 compatibility (+ Drush 12 during development) needs to be maintained. In my opinion it should not be maintained because there isn't security support anyway and we can update the minor version in line with #357742 🌱 Guidelines for semantic versioning and Drupal core support Active .