Explain early when Google sign-in won't work because the app was opened from a social app

Previously, tapping the Google button after opening the sign-in screen through a social app would never complete, and users often gave up.

In these situations the Google button is now disabled, with guidance to continue by email instead or reopen the screen in a normal browser.

You no longer retry an action that can't work, so both sign-up and sign-in proceed more smoothly.