Fix quantized ONNX: MatMul-only quant (ConvInteger unsupported in onnxruntime-web)

onnx/decoder_model_merged_quantized.onnx

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:d3f4e464ff6b010de29d1b6e74968d72cb5e7a8d951818e172ff4b9a69511428
-size 195096949
+oid sha256:b392f66f6851cf1a818cfc7d511270ed17e0c37c4bd165e68d8e1800ec110f95
+size 315624573

onnx/encoder_model_quantized.onnx

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:12ff076d858088e001c2e0e24579431c846772224c27038034d23027691b9f89
-size 92216514
+oid sha256:4ef4854e09d24e8335d4420ada7933726ce28396e8dc90f6bdbeb9b925aaca10
+size 98075781