cron: fix deletion of unactivated accounts

cron: fix deletion of unactivated accounts

There is a test in expire_notifications() that tries to check if
the user's last login matches the date joined. (I think the login
date is not set until a post-activation login.) This does not work:
on patchwork.ozlabs.org there are 10k users that have never been
deleted.

Drop the date test: it should be sufficient that a user is not
active and their confirmation is not pending.

Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Stephen Finucane <stephen@that.guru>