[Epic] Replication stabilization: fix all known issues

[art-dr]

Total: 12sp

Dev board ref: https://github.com/tarantool/roadmap-internal/issues/63, https://github.com/tarantool/roadmap-internal/issues/56
PM ref: https://www.notion.so/tarantool/Replication-stabilisation-fix-all-known-issues-part-2-3ab09b7374ad4b7dbd5eefb4c9c25125

SME: @ sergepetrenko

Tech debt

• replication: the truncate method called from within a transaction #2599
• replication: removing anonymous replicas from synchro quorum #2600
• Support dynamic evaluation of synchronous replication quorum #1730
• [3pt] Provide box.info.synchro interface #2044

Other related issues

These issues are related to replication but are not in the "Replication stabilisation" list.
Need to discuss if any of these issues should be included in this epic.

• New configuration option - replication_threads #2590
• Add box.info.replication[n].downstream.lag entry #2204
• [3pt] box.info.ro_reason #2445