9 files declare their use of ContentEntityDeleteForm in Zircon Profile 8

BlockContentDeleteForm.php in core/modules/block_content/src/Form/BlockContentDeleteForm.php

Contains \Drupal\block_content\Form\BlockContentDeleteForm.

ContentTranslationDeleteForm.php in core/modules/content_translation/src/Form/ContentTranslationDeleteForm.php

Contains \Drupal\content_translation\Form\ContentTranslationDeleteForm.

DeleteForm.php in core/modules/comment/src/Form/DeleteForm.php

Contains \Drupal\comment\Form\DeleteForm.

EntityTestDeleteForm.php in core/modules/system/tests/modules/entity_test/src/EntityTestDeleteForm.php

Contains \Drupal\entity_test\EntityTestDeleteForm.

FeedDeleteForm.php in core/modules/aggregator/src/Form/FeedDeleteForm.php

Contains \Drupal\aggregator\Form\FeedDeleteForm.

MenuLinkContentDeleteForm.php in core/modules/menu_link_content/src/Form/MenuLinkContentDeleteForm.php

Contains \Drupal\menu_link_content\Form\MenuLinkContentDeleteForm.

NodeDeleteForm.php in core/modules/node/src/Form/NodeDeleteForm.php

Contains \Drupal\node\Form\NodeDeleteForm.

ShortcutDeleteForm.php in core/modules/shortcut/src/Form/ShortcutDeleteForm.php

Contains \Drupal\shortcut\Form\ShortcutDeleteForm.

TermDeleteForm.php in core/modules/taxonomy/src/Form/TermDeleteForm.php

Contains \Drupal\taxonomy\Form\TermDeleteForm.