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>
What is the aim of regressionSuiteHpccMainEclDir if it points to download dir insted of the ecl.