Switch from PrefixRecord to PackageRecord

[lrandersson]

Description

This PR improves the changes added in #1314. It was noticed that PrefixRecord added much more metadata than necessary which bloated the info.json file. Comparing the two info.json (before/after this implementation) shows about a 70x reduction in file size when using PackageRecord.

Checklist - did you ...

• Add a file to the news directory (using the template) for the next release's release notes?
• Add / update necessary tests?
• Add / update outdated documentation?

[marcoesters]

This PR should be added to the news item.

Technically, this is a hack. PackageRecord and PrefixRecord describe two separate items (an archive file vs an installed package in an environment). Instead of coercing this into PackageRecords, could we just remove the entries we don't need in the dictionary representation/the data dump before we add it into info.json? That way, we stay correct while also removing unnecessary data.

[lrandersson]

Good call @marcoesters, see e9d8bce. However regarding the news item, we only modified the existing implementation so I would say it is already covered by https://github.com/conda/constructor/blob/main/news/1314-build-environment-info, or do you disagree?

[marcoesters]

However regarding the news item, we only modified the existing implementation so I would say it is already covered by https://github.com/conda/constructor/blob/main/news/1314-build-environment-info, or do you disagree?

Correct. So, the new item should be modified to list both PR numbers, i.e., (#1314, #1325).