Move bookmark parsing logic into LegacyBeatmapDecoder

osu.Game/Beatmaps/BeatmapInfo.cs

@@ -5,7 +5,6 @@ using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
-using System.Linq;
 using Newtonsoft.Json;
 using osu.Framework.Testing;
 using osu.Game.Database;
@@ -104,28 +103,6 @@ namespace osu.Game.Beatmaps
         /// </summary>
         public int CountdownOffset { get; set; }
 
-        // Editor
-        // This bookmarks stuff is necessary because DB doesn't know how to store int[]
-        [JsonIgnore]
-        public string StoredBookmarks
-        {
-            get => string.Join(',', Bookmarks);
-            set
-            {
-                if (string.IsNullOrEmpty(value))
-                {
-                    Bookmarks = Array.Empty<int>();
-                    return;
-                }
-
-                Bookmarks = value.Split(',').Select(v =>
-                {
-                    bool result = int.TryParse(v, out int val);
-                    return new { result, val };
-                }).Where(p => p.result).Select(p => p.val).ToArray();
-            }
-        }
-
         [NotMapped]
         public int[] Bookmarks { get; set; } = Array.Empty<int>();
 

osu.Game/Beatmaps/Formats/LegacyBeatmapDecoder.cs

@@ -201,7 +201,11 @@ namespace osu.Game.Beatmaps.Formats
             switch (pair.Key)
             {
                 case @"Bookmarks":
-                    beatmap.BeatmapInfo.StoredBookmarks = pair.Value;
+                    beatmap.BeatmapInfo.Bookmarks = pair.Value.Split(',').Select(v =>
+                    {
+                        bool result = int.TryParse(v, out int val);
+                        return new { result, val };
+                    }).Where(p => p.result).Select(p => p.val).ToArray();
                     break;
 
                 case @"DistanceSpacing":