[5.x] Replace UsesCallbackRelations with afterQuery

[Jade-GG]

ref: RAP-1811

Since Laravel v12.50.0 we can once again use afterQuery on a relation without the keys being reset (thanks to a fix made by this weird jade-gg person). This means that we don't need to use the UsesCallbackRelations trait (along with the custom relations) anymore.

This also means I was able to remove one of our TODOs relating to manually keying the prices relation after the fact during indexing.

Obviously this pins the minimum Laravel version to ^12.50.

[Jade-GG]

Neat, the prefer-lowest tests are failing because they seem to ignore the version constraint.

[royduin]

Seems like all the product prices are gone?

[Jade-GG]

Seems like all the product prices are gone?

As it turns out, we can't use non-unique keys for the afterQuery keyBy, because those will (in hindsight: obviously) overwrite each other when you're doing a query with more than one product at the same time.

This affected superAttributes and prices. So I've reverted how prices works and simplified how super attributes work in the cart, as the actual attribute id is only necessary when specifically adding the product to the cart.