For unreleased bug #23350, introduced because we're no longer
cascade-deleting _all_ related installs (related to #22996, #21654,
#22087)
# Checklist for submitter
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [x] Added/updated tests
- [x] Manual QA for all new/changed functionality