Remove field and cron

Remove this line: https://git.vauxoo.com/vauxoo/xunnel-account/blob/d6d03eee73290769da1fa01a0e48be793c12fb3c/account_xunnel/models/res_company.py#L65

Updated

• Remove cron for xunnel providers.
• Remove field xunnel_providers_last_sync

Sync providers are not needed a cron since that there are not bank account created daily, then the field of last_sync is not needed either.