qemu: Fix job handling in qemuDomainSetMetadata

The code modifies the domain configuration but doesn't take a MODIFY
type job to do so.

src/qemu/qemu_driver.c

@@ -17306,10 +17306,15 @@ qemuDomainSetMetadata(virDomainPtr dom,
     if (!(caps = virQEMUDriverGetCapabilities(driver, false)))
         goto cleanup;
 
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
+        goto cleanup;
+
     ret = virDomainObjSetMetadata(vm, type, metadata, key, uri, caps,
                                   driver->xmlopt, cfg->stateDir,
                                   cfg->configDir, flags);
 
+    qemuDomainObjEndJob(driver, vm);
+
  cleanup:
     qemuDomObjEndAPI(&vm);
     virObjectUnref(caps);