False confirmation for restricted Google Drive photos

[cwang360]

Photos not shared to "anyone with link can view" are still visible in preview (and published event page) if the user is signed into personal Google account in browser. The expected behavior is the red error message on the modal

Error: Image could not be loaded. Please make sure a valid Google Drive file ID (not link) is entered, and the image is shared to everyone with link.

after the user enters their file ID. This can cause confusion if people think their photos are visible but aren't visible to others on the published page.