Fix "Older than" relative date inputs

[schlick]

The "older than" relative date options are often used to exclude records that occur on a weekly or fortnightly basis. For example, for events that occur every Monday you could use the "Older than 7 days" option to generate alerts for ones that are overdue, not due today (via a last occurred on date). If the current date is Monday 29/03/21 then 7 days ago is Monday 22/03/21. You don't want to include the events that took place on that previous Monday. So you need the filter to be more than 7 days ie Sunday 21/03/21. So "Older than 7 days" ought to use an exclusive to date.