Instance rebootstrap with new UUID but same ID and name

Product: Tarantool
Since: 3.0
Root document: box.cfg.instance_name section
SME: @ Gerold103

Should be done together with #3468 (or after it)

If an instance has a non-empty instance name
(box.cfg.instance_name), then at rebootstrap it can keep the
name and its old numeric ID (space _cluster['id'] field).

This might be needed if one doesn't want to pollute _cluster
with new rows, and somewhy doesn't want to or can't just drop the
rows belonging to the dead replicas.

In order for this to work 1) the rebootstrapping replica must keep
its old non-empty instance name, 2) the other instances should not
have any alive connections to the old dead replica. Ideally, the
old replica should be just deleted from box.cfg.replication
everywhere.

When that works, the old row in _cluster is automatically
updated with the new instance UUID.
Requested by @Gerold103 in https://github.com/tarantool/tarantool/commit/4507c59de6af427a4a8f7847fe6c1c31d3e7eacc.

Start with the box.cfg.instance_name section in the root document and review the related issue #3468. Confirm the documented rebootstrap conditions, including retaining the name and numeric ID and removing old replica connections. Done means the behavior, prerequisites, and _cluster update are clearly documented.