Fix: container-wrapper: size container operation can throw

Fix: container-wrapper: size container operation can throw

  1512923 Uncaught exception
  If the exception is ever thrown, the program will crash.

  In lttng::​utils::​random_access_container_wrapper<lttng_action const *, lttng_action const *, lttng::​ctl::​details::​const_action_list_operations>::​size(): A C++ exception is thrown but never caught (CWE-248)

Reported-by: Coverity Scan
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I5f8bffc64fb239e59b272985f6b3c959d238da0a