run-nm-test: Just use exec instead of running and exiting

tools/run-nm-test.sh

@@ -231,8 +231,7 @@ fi
 if ! _is_true "$NMTST_USE_VALGRIND" 0; then
     export NM_TEST_UNDER_VALGRIND=0
     "${NMTST_DBUS_RUN_SESSION[@]}" \
-    "$TEST" "$@"
-    exit $?
+    exec "$TEST" "$@"
 fi
 
 if [[ -z "${NMTST_VALGRIND}" ]]; then