Fix quorum queue status calculation to ignore non-voters

[illotum]

Proposed Changes

Fix: calculating qq status will ignore non-voters in cluster size calculation.
Add: list voters over HTTP API (via rabbit_quorum_queue:format/1).

Types of Changes

• Bug fix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• Documentation improvements (corrections, new content, etc)
• Cosmetic change (whitespace, formatting, etc)
• Build system and/or CI

Checklist

• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• I have added tests that prove my fix is effective or that my feature works
• All tests pass locally with my changes
• If relevant, I have added necessary documentation to https://github.com/rabbitmq/rabbitmq-website
• If relevant, I have added this change to the first version(s) in release-notes that I expect to introduce it

Further Comments

• I have mixed feelings about adding RPC for every queue in a potential list of hundreds, but couldn't think of an alternative.

[illotum]

Opening for review. This PR

• Pulls newly minted ra 2.8.0
• Bumps Elixir predicate to 1.17. I keep adding and reverting it on various branches, it's probably time to commit. But LMK if you prefer a standalone PR!
• Exposes voters in quorum queue format. I have mixed feelings about adding RPC for every queue in a potential list of hundreds, but couldn't think of an alternative.

[michaelklishin]

@illotum can we use ra_server_proc:local_state_query/3 directly in RabbitMQ and not bump Ra? We will bump it for 3.13 but before rabbitmq/ra#411 (comment) is addressed, likely cannot adopt a new version immediately.

[illotum]

Reverted to direct state_query (and pruned everything unrelated).

[kjnilsson]

I think this change will make the /queues HTTP API slower when there are many queues. It will need testing but I can't approve as is.

[kjnilsson]

whitespace

[kjnilsson]

this function is called for every queue when using the /queues HTTP API, depending on sort columns this could mean all queues in the system. Please compare HTTP API query times with and without this change with 5k quorum queues in a 3 node cluster.

I think we need to find another way of achieving this. Perhaps we need to persist the voting set in the queue record queue type state

[michaelklishin]

Closing per discussion with @illotum @kjnilsson. Unlike #10304, this PR needs to be reworked from scratch.

Since this change does not break anything and is arguably a bug fix, we can ship it in a 3.13.x patch in case a revised version does not make it in time for 3.13.0.