All snitch drivers are supposed to snitch info on some shard and
replicate the dc/rack info across others. All, but azure really do so.
The azure one gets dc/rack on all shards, which's excessive but not
terrible, but when all shards start to replicate their data to all the
others, this may lead to use-after-frees.
fixes: #10494
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>