Update MXFP8 refit test for source metadata API

Signed-off-by: seonjinn <sna@nvidia.com>

Author: seonjinn

tests/unit/models/policy/test_megatron_worker.py

@@ -2745,7 +2745,7 @@ def _iter_params():
 
     worker._iter_params_with_optional_kv_scales = _iter_params
 
-    info = worker._prepare_source_refit_info("hf_export")
+    info = worker._prepare_source_refit_info()
 
     assert worker._refit_prequant_names == set()
     assert info[name] == (torch.Size([2, 64]), torch.bfloat16)