Supervised failover + Tarantool Config Storage

[TarantoolBot]

<…>mous replicas are not considered as candidates to be a master.

|If a remote etcd-based storage is used to maintain the state of failover coordinators, you can also perform a manual failover.|

Active and passive coordinators
To increase fault tolerance, <…>

https://www.tarantool.io/en/doc/latest/platform/replication/supervised_failover/

Starting from Tarantool v3.3 manual failover can be performed also with Tarantool-based remote config storage (aka Tarantool Config Storage).

[Totktonada]

Correction: starting from 3.3. See https://github.com/tarantool/tarantool-ee/issues/870 and https://github.com/tarantool/enterprise_doc/issues/291.

[elhimov]

Correction: starting from 3.3. See tarantool/tarantool-ee#870 and tarantool/enterprise_doc#291.

Thanks for correction! Updated in description.
My bad... I was thinking about 3.3.0 and somehow it turned into 3.0 in my report.

[lenkis]

As I see it, here we'll need to:

• in doc 3.3+ revise all text entries that mention "external etcd-based storage" and, where applicable, extend the entries to say "external storage, etcd- or Tarantool-based";
• add info to the "Supervised failover" section (https://www.tarantool.io/en/doc/latest/platform/replication/supervised_failover) saying how to perform all actions there using Tarantool config storage (currently this section documents only etcd-based scenarios).

Point 1 to be done within this ticket.

Point 2 -- within #5384