The 'states' argument of get_shard_ranges() should be a list of ints,
but previously just a single int was tolerated. This was unnecessary
and led to inconsistent usage across call sites.
We'd like similar ContainerBroker methods, such as the anticipated
get_namespaces() [1], to have an interface consistent with
get_shard_ranges(), but not continue the unnecessary pattern of
supporting both a list and a single int argument for 'states'. This
patch therefore normalises all call sites to pass a list and
deprecates support for just a single int.
[1] Related-Change: If152942c168d127de13e11e8da00a5760de5ae0d
Change-Id: I056cefbf0894dbc68b9a6eb3d76ec4dc0a72de0d
f3a32367bf