qtest/qom-test: Traverse entire QOM tree

This test traverses the QOM sub-tree rooted at /machine.  Traverse the
entire tree instead.

The x86_64 test runs some 40 additional QMP commands, and stays under
5s for me.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-ID: <20250725135034.2280477-4-armbru@redhat.com>
Reviewed-by: Steve Sistare <steven.sistare@oracle.com>

tests/qtest/qom-test.c

@@ -211,7 +211,7 @@ static void test_machine(gconstpointer data)
 
     test_properties(qts, "/machine", true);
 
-    qlist_append_str(paths, "/machine");
+    qlist_append_str(paths, "/");
     test_list_get(qts, paths);
     test_list_get_value(qts);