Allow subclasses to redefine autosave callbacks for associated records

[numbata]

Summary

This addresses this issue #33305

AutosaveAssociation skip creation of callback method if it's already defined (even in parent class).

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[bogdanvlviv]

Thanks.
Could you please fix rubocop issues in https://codeclimate.com/github/rails/rails/pull/33378?

[bogdanvlviv]

Missing dot after #33305

[bogdanvlviv]

Extra empty line

[bogdanvlviv]

IN => In. I would also add suffix WithAcceptsNestedAttributes.

[bogdanvlviv]

Could you change order of arguments since assert_equal receive expected value as first argument and actual values as the second.
It would improve error message:

Expected: "Initial"
  Actual: "Updated"

[bogdanvlviv]

Could you change the order of arguments since assert_equal receive an expected value as the first argument and an actual values as the second.
It would improve error message:

Expected: "Initial"
  Actual: "Updated"

[numbata]

@bogdanvlviv Sure. Can i squash commits into one after?

[bogdanvlviv]

Could you squash commits into one?

[bogdanvlviv]

Not sure, but maybe it would be better to move this class definition to activerecord/test/models/company.rb

[numbata]

Actually, I'm not sure too. This specific class used in this specific place only. It should be useless in other cases. Especially when activerecord/test/models/company.rb full of other classes.

Also maybe i should move this spec to activerecord/test/cases/nested_attributes_test.rb?