Unreviewed, reverting 274906@main.

https://bugs.webkit.org/show_bug.cgi?id=269633

View Transitions is a long way from stable, the current "testable" state is appropriate

Reverted changeset:

"[view-transitions] Enable by default"
https://bugs.webkit.org/show_bug.cgi?id=269632
https://commits.webkit.org/274906@main

Canonical link: https://commits.webkit.org/274907@main

Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml

@@ -7407,16 +7407,16 @@ ViewGestureDebuggingEnabled:
 ViewTransitionsEnabled:
   type: bool
   category: animation
-  status: stable
+  status: testable
   humanReadableName: "View Transitions"
   humanReadableDescription: "Enable the View Transitions API"
   defaultValue:
     WebKitLegacy:
-      default: true
+      default: false
     WebKit:
-      default: true
+      default: false
     WebCore:
-      default: true
+      default: false
 
 VisibleDebugOverlayRegions:
   type: uint32_t