fix(dsrepl): anticipate and handle nodes leaving the cluster

[keynslug]

Fixes EMQX-12365.

Release version: v5.7

Summary

Attempt to bring together the DS's view of the cluster with mria/ekka's view and related operations, e.g. leave and force-leave.

PR Checklist

Please convert it to a draft if any of the following conditions are not met. Reviewers may skip over until all the items are checked:

• Added tests for the changes
• Added property-based tests for code which performs user input validation
• Changed lines covered in coverage report
• Change log has been added to changes/(ce|ee)/(feat|perf|fix|breaking)-<PR-id>.en.md files
• For internal contributor: there is a jira ticket to track this change
• Created PR to emqx-docs if documentation update is required, or link to a follow-up jira ticket
• Schema changes are backward compatible

[ieQu1]

Q: is it possible to display emqx_ds_replication_layer_meta:replica_set_transitions in the status?

[ieQu1]

The output looks a bit crooked:

THIS SITE:
D8894F95DC86DFDB

SITES:
5C6028D6CE9459C7    'emqx@n2.local'        up
D8894F95DC86DFDB    'emqx@n1.local'        up
F4E92DEA197C8EBC    'emqx@n3.local'        up

SHARDS:
Shard                         Replicas
messages/0                        5C6028D6CE9459C7
messages/1                        5C6028D6CE9459C7
messages/10                       5C6028D6CE9459C7
messages/11                       5C6028D6CE9459C7
messages/2                        5C6028D6CE9459C7
messages/3                        5C6028D6CE9459C7
messages/4                        5C6028D6CE9459C7
messages/5                        5C6028D6CE9459C7
messages/6                        5C6028D6CE9459C7
messages/7                        5C6028D6CE9459C7
messages/8                        5C6028D6CE9459C7
messages/9                        5C6028D6CE9459C7

[keynslug]

The output looks a bit crooked:

Yeah, that's a consequence of that space is now used for markers denoting down / non-existent sites. 🫠 Will fix in a followup.

[emqxqa]

TestExecution