tests: make auto-source-discovery-{log_level,params} tests use sink.text.details

For the same rationale as the previous patch, change how the test
component classes for test_auto_source_discovery_params and
test_auto_source_discovery_log_level report what they receive from a
print to stdout to stream name.

Change-Id: I62405ccd1fbdbe708fbec5dacc52894d4060dfb0
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1864
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Tested-by: jenkins <jenkins@lttng.org>