HPCC-11545 Use dirty flag for QueryFilesInUse cache

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
HPCC-11545 Updated based on review

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
HPCC-11545 Updated based on review

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5957 from afishbeck/dirtyFilesInUse

HPCC-11545 Use dirty flag for QueryFilesInUse cache

Reviewed-By: Gavin Halliday <gavin.halliday@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>