Use of XMP metadata in Khoj Image Search is broken. Disable by default

- CLIP Image score and XMP metadata score are not combining well.
  When combined they give non sensical results. Enable only once
  figure how best to combine the two.

- Show scores with higher precision for image search
  - Image search scores seem to be mostly be between 0.2 - 0.3 for some reason
  - Higher precision scores make it easier to understand the quality
    of returned results perceived by the model itself

src/utils/constants.py

@@ -30,7 +30,7 @@ default_config = {
             'input-filter': None,
             'embeddings-file': '~/.khoj/content/image/image_embeddings.pt',
             'batch-size': 50,
-            'use-xmp-metadata': True
+            'use-xmp-metadata': False
         },
         'music': {
             'input-files': None,