do not use manager with gdb *by default*

mysql-test/mysql-test-run.sh

@@ -226,8 +226,6 @@ while test $# -gt 0; do
 	$ECHO "Note: you will get more meaningful output on a source distribution compiled with debugging option when running tests with --gdb option"
       fi
       DO_GDB=1
-      # We must use manager, as things doesn't work on Linux without it
-      USE_MANAGER=1
       USE_RUNNING_SERVER=""
       ;;
     --client-gdb )