Fix custom code saving (#37716)

* Firstly: Better detection of when we're a custom class

* Trigger tests

* Let's break everything

* make fixup

* fix mistaken line doubling

* Let's try to get rid of it from config classes at least

* Let's try to get rid of it from config classes at least

* Fixup image processor

* no more circular import

* Let's go back to setting `_auto_class` again

* Let's go back to setting `_auto_class` again

* stash commit

* Revert the irrelevant changes until we figure out AutoConfig

* Change tests since we're breaking expectations

* make fixup

* do the same for all custom classes

* Cleanup for feature extractor tests

* Cleanup tokenization tests too

* typo

* Fix tokenizer tests

* make fixup

* fix image processor test

* make fixup

* Remove warning from register_for_auto_class

* Stop adding model info to auto map entirely

* Remove todo

* Remove the other todo

* Let's start slapping _auto_class on models why not

* Let's start slapping _auto_class on models why not

* Make sure the tests know what's up

* Make sure the tests know what's up

* Completely remove add_model_info_to_*

* Start adding _auto_class to models

* Start adding _auto_class to models

* Add a flaky decorator

* Add a flaky decorator and import

* stash commit

* More message cleanup

* make fixup

* fix indent

* Fix trust_remote_code prompts

* make fixup

* correct indentation

* Reincorporate changes into dynamic_module_utils

* Update call to trust_remote_code

* make fixup

* Fix video processors too

* Fix video processors too

* Remove is_flaky additions

* make fixup