Hardcoded recurrent event duration

When importing an .ics file with a recurrent event which has no end set (i.e. it will recur forever), fullcalendar sets a hardcoded limit of 5 years for event recurrence.

This can cause issues when recurrent events are older (like birthdays being defined starting with the date of birth, like 1996-04-02), in which case the events are imported, but don't show up in the calendar view (since fullcalendar makes them stop after 5 years, instead of recurring infinetly).

A workaround for this is to edit the XWiki pages which contain the Events, removing the `Last occurrence of the event` field.

Example .ics file:

BEGIN:VCALENDAR
PRODID:Recurrent infinity
VERSION:2.0
CALSCALE:GREGORIAN
X-WR-CALNAME:Recurrent infinity
BEGIN:VEVENT
RRULE:FREQ=DAILY
UID:0000
DTSTAMP:20260414T150713Z
DTSTART;VALUE=DATE:19960101
DTEND;VALUE=DATE:19960102
SUMMARY:Daily event
END:VEVENT
END:VCALENDAR