tests bsim edtt: Kill stuck processes in the same way as other tests

This test keeps its own partial way of running tests.
Let's have it kill stuck processes in the same way as
the rest (sending another kill 5 seconds after, and printing
a message about what happened)

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>
(cherry picked from commit 693ae863)
Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>