src.ctf.lttng-live: add lttng_live_stream_iterator destructor

src.ctf.lttng-live: add lttng_live_stream_iterator destructor

lttng_live_stream_iterator_destroy is still used for a GPtrArray, so it
is kept as a wrapper to the destructor for now.

Change-Id: Idc3fb90f2b15f44d92d9edd578783f4939474fdf
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8459
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12375
Tested-by: jenkins <jenkins@lttng.org>