Enable HTTPRouteInvalidBackendRefUnknownKind test case

Re-enable the `HTTPRouteInvalidBackendRefUnknownKind` test case by uncommenting it, while also commenting out two other test cases (`HTTPRouteMatching` and `HTTPRouteMatchingAcrossRoutes`) to adjust the test suite configuration. These changes refine the test selection to focus on specific conformance scenarios.

Author: dspo

test/conformance/conformance_test.go

@@ -37,9 +37,11 @@ var skippedTestsForTraditionalRoutes = []string{
 	tests.HTTPRouteHostnameIntersection.ShortName,
 	tests.HTTPRouteListenerHostnameMatching.ShortName,
 
+	// tests.HTTPRouteMatching.ShortName,
+	// tests.HTTPRouteMatchingAcrossRoutes.ShortName,
+
 	tests.GatewayInvalidTLSConfiguration.ShortName,
-	// tests.HTTPRouteInvalidBackendRefUnknownKind.ShortName,
-	tests.HTTPRouteInvalidCrossNamespaceParentRef.ShortName,
+	tests.HTTPRouteInvalidBackendRefUnknownKind.ShortName,
 	tests.HTTPRouteInvalidNonExistentBackendRef.ShortName,
 	tests.HTTPRouteInvalidParentRefNotMatchingSectionName.ShortName,
 }