tests: qemuxml2argv: remove validation warning

This warning is emitted for pretty much every test case,
making it hard to see what the actual error is.

Signed-off-by: Ján Tomko <jtomko@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>

tests/qemuxml2argvtest.c

@@ -527,8 +527,6 @@ testCompareXMLToArgvValidateSchemaCommand(GStrv args,
             }
 
             if (*curargs != '{') {
-                VIR_TEST_DEBUG("skipping validation of '%s': argument is not JSON",
-                               command->name);
                 arg++;
                 break;
             }