HPCC-12675 Prevent Regression Test Engine hangs when ecl command hangs.

Add timeout to "ecl run ..." command with --wait parameter.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>
Merge pull request #6719 from AttilaVamos/HPCC-12675-improvement

HPCC-12675 Prevent Regression Test Engine hangs when ecl command hangs.

Reviewed-by: Gavin Halliday <ghalliday@hpccsystems.com>