Fix CME crashes

Create a copy of the listeners list before iterating over it, and add an
assert for notification entry updates
Those should only happen on the main thread, so adding the assert will allow us
to find if that is not happening somewhere in the notification pipeline.

Fixes: 156863310
Test: manual
Change-Id: I157dafdba0c1cecb26dd7e969f3be26ca4e45472