HPCC-7832 assert.ecl regression test line change in output

To enable to run assert.ecl with the new Regression Suite and fix the problem:

1. Move testing/ecl/key/assert.xml to testing/regress/ecl/key directory.
2. Modify it to handle changed error format.
3. Move testing/ecl/assert.ecl to testing/regress/ecl directory.

This change tested on thor, hthor and roxie clusters with new query feature
of Regression Suite.

Signed-off-by: Attila Vamos <attila.vamos@gmail.com>