Fix: flt.lttng-utils.debug-info: extra colon in `bin` member

Fix: flt.lttng-utils.debug-info: extra colon in `bin` member

There is an extra ':' character in the `bin` member of the `debug-info`
field.

Example of the issue from the tests:
   debug_info = { bin = "libhello_so:+0x15a6", func = "bar+0xa9", src =
   "libhello.c:13" }

The "libhello_so:+0x15a6" will now be printed "libhello_so+0x15a6".

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: Ie7c4ea54e534eeb8a1bdd503760b791a01aa9594
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1129
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>