Revert low cpu mem tie weights (#29135)

* Revert "Add tie_weights() to LM heads and set bias in set_output_embeddings() (#28948)"

This reverts commit 725f4ad1cc.

* Revert "Patch to skip failing `test_save_load_low_cpu_mem_usage` tests (#29043)"

This reverts commit 4156f517ce.

tests/models/musicgen/test_modeling_musicgen.py

@@ -1144,10 +1144,6 @@ class MusicgenTest(ModelTesterMixin, GenerationTesterMixin, PipelineTesterMixin,
 
             self.assertNotIn(config.pad_token_id, output_generate)
 
-    @unittest.skip("Fails with - TypeError: _weight_norm_interface() missing 1 required positional argument: 'dim'")
-    def test_save_load_low_cpu_mem_usage(self):
-        pass
-
 
 def get_bip_bip(bip_duration=0.125, duration=0.5, sample_rate=32000):
     """Produces a series of 'bip bip' sounds at a given frequency."""