Show deleted shipping methods for shipping rates

Fixes #4328
payment_method_spec: avoid INSERT in before(:all)

This before(:all) block (which is outside of the database transaction
that specs are run in) was creating four payment methods which caused
order_spec to fail occasionally.

This changes it to a normal before block.

Fixes #4372
Don't assert that find is called in ShippingMethodsController spec

We only care that it returns the object we want, not that it's called

This has the added side-effect of fixing the failing tests