maintenance: fix launchctl calendar intervals

When using the launchctl scheduler, the weekly job runs daily, and the daily job runs on the first six days of each month. This appears to be due to specifying "Day" in the calendar intervals, which according to launchd.plist(5) is for specifying days of the month rather than days of the week. The behaviour of running a job on the 0th day is undocumented, but in my testing appears to be the same as not specifying "Day" in the calendar interval, in which case the job will run daily. Use "Weekday" in the calendar intervals, which is the correct way to schedule jobs to run on specific days of the week. Signed-off-by: Josh Heinrichs <joshiheinrichs@gmail.com> Acked-by: Derrick Stolee <stolee@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>