fix: make sure columns are fully qualified in aggregates (#5629)
Restores the original behavior where group by aggregations would have
column names with explicit table names. This behavior cannot be used
with non-group-by aggregates, because they sometimes rely on referring
to columns from a subquery.
[TML-1483](https://linear.app/prisma-company/issue/TML-1483/fix-groupby-regression)
Fixes https://github.com/prisma/prisma/issues/28084