src.ctf.fs: remove ctf_fs_ds_group_medops_data_destroy

src.ctf.fs: remove ctf_fs_ds_group_medops_data_destroy

Remove it, simply delete `data` in the custom deleter.  Note that we
still use a custom deleter because ctf_fs_ds_group_medops_data is in the
.cpp file, and therefore not visible to other compilation units.  We
could move it to the .hpp to avoid this, but it's going to be removed
soon anyway, so it's not worth it.

Change-Id: Ib5741e0e0a535cb84b2a4e27ff6ff9620eaaebce
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/8273
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/12311
Tested-by: jenkins <jenkins@lttng.org>