Fix crash when debugging exception

Fixes a crash when detaching the debugger during an exception event. The cause
is a concurrent modification of Instrumentation::exception_caught_listeners_
list (consequence of debugger being detached) while we loop over its elements.

Workaround the issue by making a copy of the listeners list.

Bug: 13738672
Change-Id: I56b84c5c8f31d6fbda1ba7cb35caeefc5e7ca60f