fix: recent changes to telethon sessions leave ghost files

[msramalho]

applies to telethon_archiver and tbot_archiver

the logic in https://github.com/bellingcat/auto-archiver/blob/601572d76e19d24ce1c3e8881b15d23a4bea987e/src/auto_archiver/archivers/telethon_archiver.py#L102-L105 (for telethon) is not being properly called everytime and so ghost .session files are left behind.