fix: do not render default schema when dropping items in it (#5675)
[TML-1527](https://linear.app/prisma-company/issue/TML-1527/regression-in-616-migrate-adds-explicit-schema-when-dropping-table)
We need some special handling when dropping items in the default schema.
More explanation in comments.
Fixes https://github.com/prisma/prisma/issues/28312