src.ctf.lttng-live: use std::vector in lttng_live_get_one_metadata_packet

src.ctf.lttng-live: use std::vector in lttng_live_get_one_metadata_packet

Use an std::vector to manage the buffer used to store the received data.

Change-Id: I04f99440573c722d982378ef9d8bb47f35b343aa
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8413
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12349
Tested-by: jenkins <jenkins@lttng.org>