HPCC-11563 Don't set RefFileNotFound for ReferencedFiles in packagemap

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5976 from afishbeck/pmAddFalseDfsNotFound

HPCC-11563 Don't set RefFileNotFound for ReferencedFiles in packagemap 

Reviewed-By: Gavin Halliday <gavin.halliday@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>