ActiveSupport patches Kernel to add `class_eval` but this behavior wasn't
loaded in the test environment. This created a discrepancy between test
and prod, causing tests to fail that should have passed and vice versa.
Fully loading ActiveSupport makes the test environment more accurate.

The goal of ClassMethodsProxy is to avoid polluting the target's namespace,
but it was possible to do this by accident when calling `class_eval` before
ActiveSupport was completely loaded. This test ensures the namespace isn't
polluted, regardless of the load state of ActiveSupport.

This PR switches the elasticsearch-rails gem to use a new signature
of the ActiveSupport::LogSubscriber#color method when called in an
app using Rails 7.1+. With older Rails, the gem uses the working, old
signature.