swift: bump rsync max connections

The 2/2/3 thresholds for account/container/object respectively are
probably too conservative, especially in a cluster of 15 nodes now. Bump
these to 5/5/10 in an entirely unscientific manner (i.e. just a guess).

Change-Id: Ib5a18e3f8d9450d3f99bb407a16bf5d90614c296