Merge pull request #15812 from peppy/realm-live-unmanaged-fetch-fix

Avoid attempting to fetch a non-managed `RealmLive` instance from the realm backing

osu.Game/Database/EntityFrameworkLive.cs

@@ -11,6 +11,7 @@ namespace osu.Game.Database
     {
         public EntityFrameworkLive(T item)
         {
+            IsManaged = true; // no way to really know.
             Value = item;
         }
 
@@ -31,6 +32,8 @@ namespace osu.Game.Database
             perform(Value);
         }
 
+        public bool IsManaged { get; }
+
         public T Value { get; }
 
         public bool Equals(ILive<T>? other) => ID == other?.ID;