HPCC-8459 Fix incorrect ESP log when file not deleted

When a logical file cannot be deleted and the queryDistribut
edFileSystem().remove() does not return error message, ESP log
shows "Deleted Logical File: ...". This fix checks the return
of the remove(). If the remove() returns 'not deleted', ESP will show
the problem.

Signed-off-by: Kevin Wang <kevin.wang@lexisnexis.com>