test(proxy): cover a registry model priced only via tiered_pricing

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

Author: mateo-berri

tests/test_litellm/proxy/auth/test_auth_checks.py

@@ -6611,6 +6611,7 @@ def test_model_has_no_cost_mapping_no_model_or_router_is_false():
         "azure/speech/azure-tts",
         "mistral/mistral-ocr-latest",
         "vertex_ai/imagen-3.0-generate-001",
+        "dashscope/qwen-flash",
     ],
 )
 def test_model_has_no_cost_mapping_non_token_priced_model_is_false(underlying_model):