`CalendarRepository.findMany` holds every result back by 500 ms, which
was added for the calendar widget to collapse bursts of plugin and
permission changes. `debounce` delays the first result too, so the
agenda part - whose ranking stays 0 until the first result arrives -
only appeared half a second after the clock and the other parts.
The agenda is re-queried on a calendar change or every 15 minutes, so
it does not need the debounce. Make the delay a parameter (still 500 ms
by default) and pass 0 from `CalendarPartProvider`.