Revert "Exit import process after first handler is run"

This reverts commit 4139301afa.

osu.Game/OsuGameBase.cs

@@ -362,10 +362,7 @@ namespace osu.Game
             foreach (var importer in fileImporters)
             {
                 if (importer.HandledExtensions.Contains(extension))
-                {
                     await importer.Import(paths);
-                    continue;
-                }
             }
         }