maintenance: fix systemd schedule overlaps

maintenance: fix systemd schedule overlaps

The 'git maintenance run' command prevents concurrent runs in the same
repository using a 'maintenance.lock' file. However, when using systemd
the hourly maintenance runs the same time as the daily and weekly runs.
(Similarly, daily maintenance runs at the same time as weekly
maintenance.) These competing commands result in some maintenance not
actually being run.

This overlap was something we could not fix until we made the recent
change to not use the builting 'hourly', 'daily', and 'weekly' schedules
in systemd. We can adjust the schedules such that:

 1. Hourly runs avoid the 0th hour.
 2. Daily runs avoid Monday.

This will keep maintenance runs from colliding when using systemd.

Signed-off-by: Derrick Stolee <derrickstolee@github.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>