chore: enforcement of dbauthz tests was broken (#11218)

* chore: enforcement of dbauthz tests was broken

Implemented missing tests to catch back up

---------

Co-authored-by: Cian Johnston <cian@coder.com>

coderd/database/dbmem/dbmem.go

@@ -880,7 +880,7 @@ func (q *FakeQuerier) AllUserIDs(_ context.Context) ([]uuid.UUID, error) {
 	defer q.mutex.RUnlock()
 	userIDs := make([]uuid.UUID, 0, len(q.users))
 	for idx := range q.users {
-		userIDs[idx] = q.users[idx].ID
+		userIDs = append(userIDs, q.users[idx].ID)
 	}
 	return userIDs, nil
 }