Do chuncked job deletion

This is helpful in cases where we are deleting tons jobs at the same
time in a gallera cluster. This doesn't happen often but this can create
issues.

Test plan:

1. Use https://github.com/nextcloud/quota_warning/pull/88


2. Change max to 1
3. Enabled/Disable quota_warning app and see jobs getting sucessfully
   added and removed

Signed-off-by: Carl Schwan <carl@carlschwan.eu>