🚨 Remove Group Beam Search decoding strategy

[manueldeprada]

Removes Group Beam Search generation strategy from the codebase. Directs users to the transformers-community/group-beam-search repository.

It has been a warning for a few releases, but now trust_remote_code=True is required to run group beam search.

Depends on #40480

[manueldeprada]

Note that if we remove this, initializing config arguments on the model will stop working, as in

transformers/tests/generation/test_utils.py

Lines 2837 to 2848 in 52aaa3f

	model = BartForConditionalGeneration.from_pretrained(
	"hf-internal-testing/tiny-random-bart",
	max_length=10,
	num_beams=2,
	num_beam_groups=2,
	num_return_sequences=2,
	diversity_penalty=1.0,
	eos_token_id=None,
	return_dict_in_generate=True,
	output_scores=True,
	length_penalty=0.0,
	)

[manueldeprada]

I moved the gen args to a gen config instead of model config, see previous comment.

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint. The docs are available until 30 days after the last update.

[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: csm, dia, janus, musicgen, musicgen_melody, recurrent_gemma, rwkv

[manueldeprada]

build-doc

[github-actions]

Building docs for all languages...

[gante]

(from a quick glance, the changes are the same as in the CS PR, which I already approved)