[flutter_runner_tests] Use old method from libsys

We were using CreateWithRequest2 method which was there for soft
transition, revert to using old one now that it is fixed.

Change-Id: I156832db30e7b5250caf1c8d0d28a97cae4474bc
diff --git a/runtime/flutter_runner/fuchsia_font_manager_unittest.cc b/runtime/flutter_runner/fuchsia_font_manager_unittest.cc
index ef4ed6b..94b5b03 100644
--- a/runtime/flutter_runner/fuchsia_font_manager_unittest.cc
+++ b/runtime/flutter_runner/fuchsia_font_manager_unittest.cc
@@ -40,7 +40,7 @@
 
     zx::channel out_services_request;
     auto font_services =
-        sys::ServiceDirectory::CreateWithRequest2(&out_services_request);
+        sys::ServiceDirectory::CreateWithRequest(&out_services_request);
     auto launch_info_font_service = GetLaunchInfoForFontService();
     launch_info_font_service.directory_request =
         std::move(out_services_request);