Merge branch 'ds/maintenance-part-2'

"git maintenance", an extended big brother of "git gc", continues to evolve. * ds/maintenance-part-2: maintenance: add incremental-repack auto condition maintenance: auto-size incremental-repack batch maintenance: add incremental-repack task midx: use start_delayed_progress() midx: enable core.multiPackIndex by default maintenance: create auto condition for loose-objects maintenance: add loose-objects task maintenance: add prefetch task