tests: switch from -mon to -object monitor-qmp

Use the new preferred low level option for configuring the
QMP service in libqtest and the python Machine class used
by tests. This will avoid triggering deprecation warnings
after the subsequent commit.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-ID: <20260706135824.2623960-34-berrange@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

python/qemu/machine/machine.py

@@ -304,8 +304,8 @@ class QEMUMachine:
                 )
             else:
                 moncdev = f"socket,id=mon,path={self._monitor_address}"
-            args.extend(['-chardev', moncdev, '-mon',
-                         'chardev=mon,mode=control'])
+            args.extend(['-chardev', moncdev, '-object',
+                         'monitor-qmp,id=qmp,chardev=mon'])
         return args
 
     def _console_args(self, interactive: bool = False) -> List[str]:

tests/qtest/libqtest.c

@@ -460,7 +460,7 @@ gchar *qtest_qemu_args(const char *extra_args)
                       "-qtest unix:%s "
                       "-qtest-log %s "
                       "-chardev socket,path=%s,id=char0 "
-                      "-mon chardev=char0,mode=control "
+                      "-object monitor-qmp,id=qmp0,chardev=char0 "
                       "-display none "
                       "-audio none "
                       "%s "