This supports running puppet to pick up new sharding changes, which
will warn of the need to finalize them via
`refresh-sharding-and-restart`, or simply running that directly.
This allows straight-forward configuration of realm-based Tornado
sharding through simply editing /etc/zulip/zulip.conf to configure
shards and running scripts/refresh-sharding-and-restart.
Co-Author-By: Mateusz Mandera <mateusz.mandera@zulip.com>