fix 'open backup' opening to an empty deck list

Starting the import in a timer could cause the collection to be unloaded
while the deck list was being displayed, leading to an inconsistent
state.

The timer was originally required to avoid importing on startup,
but profile load is already delayed until after startup these days,
so the workaround should no longer be necessary.

aqt/importing.py

@@ -384,10 +384,8 @@ This will delete your existing collection and replace it with the data in \
 the file you're importing. Are you sure?"""), msgfunc=QMessageBox.warning,
                                               defaultno=True):
         return False
-    # schedule replacement; don't do it immediately as we may have been
-    # called as part of the startup routine
-    mw.progress.timer(
-        100, lambda mw=mw, f=importer.file: replaceWithApkg(mw, f, mw.restoringBackup), False)
+
+    replaceWithApkg(mw, importer.file, mw.restoringBackup)
 
 def replaceWithApkg(mw, file, backup):
     mw.unloadCollection(lambda: _replaceWithApkg(mw, file, backup))