When snitch reconfigures (gossiper-property-file one) it kicks storage
service so that it updates itself. This place also needs to update the
dc/rack info about itself, the correct (new) values are taken from the
snitch itself.
There's a bug here -- system.local table it not update with new data
until restart.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>