Every time a column in the projects table is changed, the Avatarable concern
would validate that the avatar file size was under 200K. This not only delays
the database changes, but it also can lead to unrelated failures if the HTTP
request fails for some reason.
Closes#51053
This is tricky: the query was being run in
`ObjectStorage::Extension::RecordsUploads#retrieve_from_store!`, but we can't
just add batch loading there, because the `#upload=` method there would use the
result immediately, making the batch only have one item.
Instead, we can pre-emptively add an item to the batch whenever an avatarable
object is initialized, and then reuse that batch item in
`#retrieve_from_store!`. However, this also has problems:
1. There is a lot of logic in `Avatarable#retrieve_upload_from_batch`.
2. Some of that logic constructs a 'fake' model for the batch key. This should
be fine, because of ActiveRecord's override of `#==`, but it relies on that
staying the same.
