filter/testing/UnitTestCoordinateSystemTransform.cxx is broken

Background: CoordinateSystemTransform filter would store the transform result as a new field on the dataset.

For this unit test, it tries to validate the filter by transforming the dataset from A->B(Ex. Cylindrical to Cartesian) then B->A'(Ex. Cartesian to Cylindrical). If the coordinates of A and A' does not match then there is something wrong. However, it never adds the newly generated field as a new coordinate system while it's using the coordinate system as the field.

The right fix should be adding the new field as a new coordinate system to the dataset then test against it.