Follow ups from !100386

🚌 Context

In Add bulk destroy mutation for Packages (!100386 - merged), we added a GraphQL endpoint to destroy packages from the Package Registry in bulk.

During the backend maintainer review, there were a few points that were not addressed and left for a follow up:

• !100386 (comment 1137177681)
• !100386 (comment 1137149223)

🤔 What does this MR do and why?

• Replace an match_array with an eq in a spec.
• Rename Packages::Package scopes that preload associations.

The above are straightforward code cleanups and there is 0 impact on existing features. As such, a changelog was not included.

📺 Screenshots or screen recordings

See !100386 (merged)

🗄 How to set up and validate locally

See !100386 (merged)

🚓 MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.