Nested disconnect fails with extendedWhereUnique on SQL

[Weakky]

Bug description

Consider this datamodel

model Parent {
  id Int @id

  childId Int? @unique
  childOpt Child? @relation(fields: [childId], references: [id])
}

model Child {
  id Int @id
  non_unique String
  parentOpt Parent?
}

And say you run this query

await prisma.parent.update({
  where: { id: 1 },
  data: {
    childOpt: { disconnect: { non_unique: 1 } }
  }
})

The query will fail on the UPDATE statement because it's lacking a join to check Child.non_unique.

Expected behavior

The query should work regardless of where the relation is inlined.

Environment & setup

• OS: macOS
• Database: Postgres 10

Prisma Version

4.7.0

[Weakky]

Related to #15837