This commit changes the default return value of `Auth::ManagedAuthenticator#primary_email_verified?` to false. We're changing the default to force developers to think about email verification when building a new authentication method. All existing authenticators (in core and official plugins) have been updated to explicitly define the `primary_email_verified?` method in their subclass of `Auth::ManagedAuthenticator` (example commit 65f57a4d05).
Internal topic: t/82084.
It's very easy to forget to add `require 'rails_helper'` at the top of every core/plugin spec file, and omissions can cause some very confusing/sporadic errors.
By setting this flag in `.rspec`, we can remove the need for `require 'rails_helper'` entirely.
