account: Replace `getAuth` in a place that wants `getIdentity`.
account: Replace `getAuth` in a place that wants `getIdentity`.

This is the one place we use `getAuth` in another selector -- which is
a sure sign that we're not going to be making an API request with it,
the main legitimate use of an `Auth` object.

vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile