fix-VaeImageProcessor-docstring (#5182)

```
do_binarize (`bool`, *optional*, defaults to `True`)
|
v
do_binarize (`bool`, *optional*, defaults to `False`)
```

src/diffusers/image_processor.py

@@ -48,7 +48,7 @@ class VaeImageProcessor(ConfigMixin):
             Resampling filter to use when resizing the image.
         do_normalize (`bool`, *optional*, defaults to `True`):
             Whether to normalize the image to [-1,1].
-        do_binarize (`bool`, *optional*, defaults to `True`):
+        do_binarize (`bool`, *optional*, defaults to `False`):
             Whether to binarize the image to 0/1.
         do_convert_rgb (`bool`, *optional*, defaults to be `False`):
             Whether to convert the images to RGB format.