Add Classic Queue version to operator policies

[SignalWhisperer]

Proposed Changes

As part of migrating to having Classic Queues version 2 by default in 3.13, the recommended way to migrate is to set a policy for queue-version: 2. As an operator, it can be difficult to have users set the policy on all of their queues. If an operator were to add a policy to set the queue version, any user setting their own higher priority custom policy but not setting the queue version would revert it back to the configured default.

This adds the Classic Queue version to operator policies, overriding the policy set by the user in favour of that set by the operator. This will allow for a smoother transition, but also will let operators decide of the underlying queue version regardless of the compliance of the users.

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

[michaelklishin]

@SignalWhisperer sorry, can you please rebase?

[michaelklishin]

No need, it did not take much time or context to resolve.

[michaelklishin]

Merged as part of #9547.