HHH 9432 Remove where clause from middle entity

As the middle entity contains only the id columns, any where-clause refering to a column of one of the associated tables leads to an sql-error, as the sql refers to an unknown column.
The lines I removed came in with commit ed2d72e492f0fb88f0dbf86440ec098dd675a1d3 to fix [HHH-4633]. But the test described there executes successfully with and without my change.