Impossible to close the interim login modal

[johnbillion]

Steps to reproduce:

1. Open a post for editing
2. Clear your cookies or log out of the site in another window
3. When autosave or heartbeat kicks in, you'll be presented with the "Session expired" modal window
4. Attempt to close the window using the X in the top right corner

Note that the modal closes but immediately re-opens. We should allow this window to be closed in case the user needs to access any of the content on the screen.

[nofearinc]

disable heartbeat-tick.wp-auth-check

[nofearinc]

Originally when hide() is called, only the beforeunload.wp-auth-check callback is disabled, but not heartbeat-tick.wp-auth-check. The latter is checking for the wp-auth-check value in the callback which can't be changed since the user is still logged out, we just don't want to display the popup constantly.

If we deactivate the heartbeat-tick.wp-auth-check event handler the popup verification will be disabled as well until the next request is processed - and IMO other AJAX requests should behave properly and prevent non-authorized activities.

[wonderboymusic]

In 35568:

Administration: when hiding the login modal and unbind the auth check, also unbind the heartbeat auth check.

Props nofearinc.
Fixes #28962.