config-geo: initial conversion to failover arrays

This is a naive first step / reformatting, there's no thought
given to load scenarios.

All location dclists are converted to arrays of 1-2 datacenters,
with the cache dcs all failing over directly to eqiad.  Basically:

s/esams,/[esams, eqiad],/
s/ulsfo,/[ulsfo, eqiad],/
s/eqiad,/[eqiad       ],/

Change-Id: Idba26213973152d6ff5f20de0a448d2a53382c06