Deprecate TransfoXL (#27607)

* fix

* fix

* trigger

* Apply suggestions from code review

Co-authored-by: Lysandre Debut <hi@lysand.re>

* tic

* revert

* revert

---------

Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>
Co-authored-by: Lysandre Debut <hi@lysand.re>

tests/test_modeling_tf_common.py

@@ -465,7 +465,6 @@ class TFModelTesterMixin:
             "TFFunnelForPreTraining",
             "TFElectraForPreTraining",
             "TFXLMWithLMHeadModel",
-            "TFTransfoXLLMHeadModel",
         ]:
             for k in key_differences:
                 if k in ["loss", "losses"]: