Revert "Fix potential crash in tests when attempting to lookup key bindings in cases the lookup is not available"

This reverts commit 8115a4bb8f.

Commit was cherrypicked out to a separate pull on a different merge
base, then reverted in that pull, so it should be reverted here too.

osu.Game/Configuration/DevelopmentOsuConfigManager.cs

@@ -14,8 +14,6 @@ namespace osu.Game.Configuration
         public DevelopmentOsuConfigManager(Storage storage)
             : base(storage)
         {
-            LookupKeyBindings = _ => "unknown";
-            LookupSkinName = _ => "unknown";
         }
     }
 }