Searches cannot find users that were deleted before upgrade

was searches (and normal searches if we fix JRADEV-21991) cannot find users that were deleted before upgrading to 6.0. so for instance if you had a user 'fred' and you deleted this user in 5.2 and he is a reporter in some issues, after upgrade 'reporter was fred' or reporter = fred will not find any matching issues.

We will only be fixing this for the current issue state, not the issue history; that is "was", "changed by" and similar searches will not work.