[formatsort] Remove misuse of 'preference'

'preference' is to be used only when the format is better that ALL qualities of a lower preference irrespective of ANY sorting order the user requests. See deezer.py for correct use of this

In the older sorting method, `preference`, `quality` and `language_preference` were functionally almost equivalent. So these disparities doesn't really matter there

Also, despite what the documentation says, the default for `preference` was actually 0 and not -1. I have tried to correct this and also account for it when converting `preference` to `quality`

youtube_dlc/extractor/go.py

@@ -236,7 +236,7 @@ class GoIE(AdobePassIE):
                 if re.search(r'(?:/mp4/source/|_source\.mp4)', asset_url):
                     f.update({
                         'format_id': ('%s-' % format_id if format_id else '') + 'SOURCE',
-                        'preference': 1,
+                        'quality': 1,
                     })
                 else:
                     mobj = re.search(r'/(\d+)x(\d+)/', asset_url)