examples/qwen3: match config with optimum flow (#15239)

Author: digantdesai

examples/models/qwen3/config/qwen3_xnnpack_q8da4w.yaml

@@ -8,8 +8,13 @@ model:
 
 quantization:
   qmode: 8da4w
+  embedding_quantize: 8,0
+
+export:
+  max_seq_length: 2048
+  max_context_length: 2048
 
 backend:
   xnnpack:
     enabled: True
-    extended_ops: True
+    extended_ops: True