Each test has its own log file within a given job result dir,
located at "test-results/$(test-id)/debug.log".

If the test is an INSTRUMENTED test, using the standard Python logging
module/API, all produced content should be recorded into the test log
file.  This adds a handler that does exactly that to the logging
module root logger.
Signed-off-by: NCleber Rosa <crosa@redhat.com>