Fix for users who are unable to sign out.

When upgrading localStorage from loggedIn to use the site namespace, I failed to remove the old loggedIn namespace, making it so users would sign out, refresh the page, and be signed in again.

fixes #3386
Add a test to ensure re-invoking upgradeLoggedInInfo does not throw an error.
Merge branch 'issue_3386_cannot_sign_out_dev' into dev

Cherry-picked commits af007b5e9a569347451b961cf07e8fe0b3bea1bf and cb6b7b1b57c66f42e204ee1a5dcf15be4782f42e

This was already r+'d as a fix to prod in issue #3398