HPCC-12015 Move the regression suite text files

Move 'download' directory

Update path generation in Test Engine

Test with ./ecl-test setup -t all, result: ok.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
HPCC-12015 Move the regression suite text files

Update after review.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #6303 from AttilaVamos/HPCC-12015-improvement

HPCC-12015 Move the regression suite text files

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>