Cherry-pick 687fbee. rdar://127259364

    [iOS] Unable to upload photos to Adobe Express app
    https://bugs.webkit.org/show_bug.cgi?id=273444
    rdar://127259364

    Reviewed by Abrar Rahman Protyasha and Wenson Hsieh.

    Adobe Express does not support HEIC photo uploads.

    Disable the setting which only transcodes HEIC photo uploads to JPEG if the
    "accept" attribute on file inputs excludes the HEIC MIME type.

    Adobe Express specifies "image/*" in order to get support for Adobe Illustrator
    files, however, they still wish to exclude HEIC. Due to a bug in CoreServices,
    they are unable to specify a specific MIME type for Illustrator files.
    Consequently, they are forced to claim support for all image types.

    Fix by restoring the old behavior.

    * Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml:

    Canonical link: https://commits.webkit.org/278196@main

Canonical link: https://commits.webkit.org/272448.962@safari-7618.2.12.10-branch

Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml

@@ -5073,7 +5073,7 @@ PhotoPickerPrefersOriginalImageFormat:
   exposed: [ WebKit ]
   defaultValue:
     WebKit:
-      default: true
+      default: false
 
 PictographFontFamily:
   type: String