Follow up on SetFakeSyncRouteForTesting

[papafe]

During the update to core 13.26.0 (#3502) the method SetFakeSyncRouteForTesting on AppHandle was added to set a fake sync route for testing "fake" local synced realm, due to the changes in core. It seems that the all the tests are passing, but there is a concern that this could cause issues down the line with actual integrations tests. We should revisit this when the core investigation is over.