We're now eager loading subclasses when loading the parent but this is far
less reliant on hacks and closer to full eager loading, which is what rails has
been pushing us to do for years.  Let's try it out.

Rails changed in 7.0 to call subclasses from reload_schema_from_cache here:
rails/rails@6f30cc0

It also changed to call descendants on the callback class (self) insead of
the ActiveSupport::DescendantsTracker here:
rails/rails@ffae3bd

We are not expecting to be called from these locations.

Avoiding descendants / subclasses calls in conditionals like this are just brittle
so we need to stop hooking through these methods:
if !%w[reload_schema_from_cache __update_callbacks descendants subclasses].include?(caller_locations.first.base_label)