HPCC-10608 Fix compressed file symbol not showing in ECLWatch

In cpp code of WsDFU, both isZipfile and ZipFile have been
renamed to 'IsCompressed'. But, the old names are still
in the existing XSLT files. This fix renames them to
'IsCompressed'.

Signed-off-by: Kevin Wang <kevin.wang@lexisnexis.com>