Retire three tiny model generators with no test consumer

[albertvillanova]

Three tiny models are generated and published but loaded by no test. This PR drops their generators.

Found by cross-referencing every push_to_hub call in the 64 generator scripts against the model ids appearing under tests/.

Tiny model	Status
tiny-Qwen2ForCausalLM-2.5-Coder	never referenced under tests/, in any commit
tiny-Qwen3MoeForSequenceClassification	was a tokenizer source only; #5469 replaced those uses with tiny-Qwen3MoeForCausalLM
tiny-PaliGemmaForConditionalGeneration	added to the DPO vision list already commented out in #2287; #4728 removed the dead comment

Why this is worth doing

An unused tiny model is not free. It is regenerated on every alignment pass, and each regeneration costs a Hub PR to open, review and merge, with no test that would notice if the result were broken.

It also makes the pre-merge check for a tiny model PR silently vacuous. apply_model_revisions in tests/conftest.py injects a revision only when a test loads that exact id, so a MODEL_REVISIONS entry for an unused model never fires: the suite goes green whether or not the regenerated artefact is sound. That is what happened on #7134, where the entry would have had no effect and the run was skipped.

Questions

CC: @huggingface/trl

Delete or revive? Deleting is the claim that these three models are not worth covering. The opposite reading is defensible, particularly for PaliGemma: it is a prefix-LM VLM, a shape no other tiny model in the suite has, and it was disabled from the moment it was added with no reason recorded, unlike the Idefics2 line above it which cites a transformers issue. If you would rather revive one, say which and I will drop that commit and open the coverage work separately. There is one commit per model, so any of the three can be dropped on its own.

What about the Hub repos? This PR only removes the generators. The repositories under trl-internal-testing stay as they are. Options are to leave them, archive them, or delete them. Leaving them means an id that still resolves, with no script left to regenerate it, which is the state that produced this cleanup in the first place. I would rather not touch the org without a decision from you.

Changes

• Drop for_causal_lm/qwen2_for_causal_lm_2_5_coder.py
• Drop for_sequence_classification/qwen3_moe_for_sequence_classification.py
• Drop for_conditional_generation/paligemma_for_conditional_generation.py

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Note

Low Risk
Deletes maintenance-only scripts with no test consumers; no runtime or library behavior changes.

Overview
Removes three unused tiny-model generator scripts under scripts/generate_tiny_models/: Qwen2.5-Coder causal LM, Qwen3 MoE sequence classification, and PaliGemma conditional generation. Each script built a shrunk config, ran smoke checks, and pushed to Hub via push_to_hub, but no test in the suite loads those published ids anymore.

This stops regenerating and opening Hub alignment PRs for models that nothing in CI would exercise. Hub repos are unchanged—only the local generators are deleted.

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