What problem does this solve or what need does it fill?

As discussed in #11690, Bevy no longer uses these types internally.

What solution would you like?

Because these are simple re-export of HashBrown types, we should just remove them from Bevy, and let users import the types themselves if needed.

Deprecating for a cycle offers a smoother migration path, as we can point users to the correct replacement.

What alternative(s) have you considered?

Just remove them immediately, which is slightly less worse but more annoying to migrate for users.

Keeping them is a poor choice, as we have no business owning all purpose hashmap types. See #11478.