change(chain): Drop transactions with unpaid actions

[upbqdn]

Motivation

Close #8609.

Specifications & References

https://zips.z.cash/zip-0317

Solution

• Rename BLOCK_PRODUCTION_UNPAID_ACTION_LIMIT to BLOCK_UNPAID_ACTION_LIMIT.
• Set BLOCK_UNPAID_ACTION_LIMIT to 0.
• Cosmetics & docs along the way.

Tests

• Adjust existing tests.
• Add a new one to check if the mempool checks can pass with valid parameters.

PR Author's Checklist

• The PR name will make sense to users.
• The PR provides a CHANGELOG summary.
• The solution is tested.
• The documentation is up to date.
• The PR has a priority label.

PR Reviewer's Checklist

• The PR Author's checklist is complete.
• The PR resolves the issue.

[arya2]

This looks good! Thank you.

[arya2]

Removed the extra-reviews label because it's not actually a consensus rule change, it only affects the transaction verifier tests for mempool requests. I reviewed it especially thoroughly since it is still sensitive code.