Steps to reproduce:

1. Observe ezpage_pages, ezpage_map_zones_pages tables.
2. Edit Ibexa Digital Experience Platform Content.
3. Page Builder opens up.
4. Add Code block.
5. Save.
6. Observe ezpage_pages, ezpage_map_zones_pages tables again.

Result:
Even though the ezpage_pages record with ID = 2 doesn't exist the relations still remain (see ezpage_map_zones_pages) - therefore the rest of the related tables (ezpage_attributes, ezpage_map_zones_pages, ezpage_attributes, ezpage_blocks, ezpage_map_attributes_blocks) are flooded.

Expected result:
When the ezpage_pages record is deleted the related page fieldtype records should be deleted as well.

Note:
The script which handles the deleting of orphaned records may prove useful. (//Update: https://github.com/mateuszbieniek/ezplatform-database-health-checker/pull/3)