test: assert the prefixed model the azure responses bridge now hands back (#37749)

a369cb0da7 made completion() hand the prefixed model back to responses(), so
that responses() running get_llm_provider() a second time becomes a no-op
instead of stripping a prefix the model id owns. That was deliberate, and it
shipped with its own unit test, but it left two older assertions behind still
expecting the bare id.

#37744 corrected the openai one in test_openai.py. This is its azure sibling,
which llm_translation_testing has been failing on ever since.

Only the expected value moves. The neighbouring custom_llm_provider assertion
already passes and stays as it is.

tests/llm_translation/test_azure_openai.py

@@ -650,7 +650,7 @@ def test_azure_openai_responses_bridge():
         mock_responses.assert_called_once()
         assert (
             mock_responses.call_args.kwargs["model"]
-            == "test-azure-computer-use-preview"
+            == "azure/test-azure-computer-use-preview"
         )
         assert mock_responses.call_args.kwargs["custom_llm_provider"] == "azure"