tests/bsim: On timeout print info to stderr

To ease diagnosing why a test fails in CI when the
CI safety timeout triggers, have the timeout command
print to stderr a message in which it indicates it has
just killed the underlaying process.

Signed-off-by: Alberto Escolar Piedras <alberto.escolar.piedras@nordicsemi.no>

tests/bsim/sh_common.source

@@ -43,6 +43,6 @@ function Execute() {
   EXECUTE_TIMEOUT="${EXECUTE_TIMEOUT:-30}"
 
   check_program_exists $1
-  run_in_background timeout ${EXECUTE_TIMEOUT} $@
+  run_in_background timeout -v ${EXECUTE_TIMEOUT} $@
 }