Get rid of handle_state_replacing

[kbr-scylla]

Since 2ec1f71 nodes no longer publish HIBERNATE state. This commit ended up in Scylla 4.6.

However, the old code for handling HIBERNATE state is still there:

        } else if (move_name == sstring(versioned_value::HIBERNATE)) {
            co_await handle_state_replacing(endpoint);

We could remove this and replace it with an ERROR message if a node publishes HIBERNATE - that is indeed an error, since it would mean we're doing replace in a mixed cluster - and with a <=4.5 node replacing one of our nodes (which would probably fail earlier anyway since the node would not pass feature check).

[kbr-scylla]

The commit is also present in scylla enterprise 2022.1.0
https://github.com/scylladb/scylla-enterprise/commit/2ec1f719de29d98e1be7fc7c171b06986b81af14

I think we can also assume that e.g. 2021.X nodes don't try to replace >=5.2 nodes (which should also fail due to a feature check)

[kbr-scylla]

Documentation must also be updated: docs/operating-scylla/procedures/cluster-management/replace-dead-node.rst mentions that the replacing node goes through hibernate state, which is wrong.