tests/test-qobject-input-visitor: Drop redundant test

test_visitor_in_alternate() tests UserDefAlternate with inadmissible
input.  test_visitor_in_fail_alternate() does basically the same.
Drop the former, keep the latter.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>

tests/test-qobject-input-visitor.c

@@ -567,7 +567,6 @@ static void test_visitor_in_alternate(TestInputVisitorData *data,
                                       const void *unused)
 {
     Visitor *v;
-    Error *err = NULL;
     UserDefAlternate *tmp;
     WrapAlternate *wrap;
 
@@ -599,11 +598,6 @@ static void test_visitor_in_alternate(TestInputVisitorData *data,
     g_assert_cmpint(tmp->u.udfu.u.value1.has_a_b, ==, false);
     qapi_free_UserDefAlternate(tmp);
 
-    v = visitor_input_test_init(data, "false");
-    visit_type_UserDefAlternate(v, NULL, &tmp, &err);
-    error_free_or_abort(&err);
-    qapi_free_UserDefAlternate(tmp);
-
     v = visitor_input_test_init(data, "{ 'alt': 42 }");
     visit_type_WrapAlternate(v, NULL, &wrap, &error_abort);
     g_assert_cmpint(wrap->alt->type, ==, QTYPE_QNUM);