Remove leftover debug call

Author: NyanCatTW1

electrum/network.py

@@ -347,7 +347,6 @@ def __init__(self, config: 'SimpleConfig', *, daemon: 'Daemon' = None):
         self._set_status(ConnectionState.DISCONNECTED)
         self._has_ever_managed_to_connect_to_server = False
         self._was_started = False
-        self.export_checkpoints("checkpoints.json")
 
         # lightning network
         if self.config.WATCHTOWER_SERVER_ENABLED: