HPCC-10610 Add DBGLOG trace of call into createSingleFileClone

Signed-off-by: Anthony Fishbeck <anthony.fishbeck@lexisnexis.com>
Merge pull request #5270 from afishbeck/createSingleFileCloneTrace

HPCC-10610 Add DBGLOG trace of call into createSingleFileClone

Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>