Tests: regression testing for lttng-relayd --group-output-by-*

Each test is run for --group-output-by-host and
--group-output-by-session and also with automatic session name and
specific session name.

No need to test against kernel. Tracing domain does not have any influence
at lttng-relayd level.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>