When upgrading from a version of slapos.core that does not support
processing instances without a connection to master to one that does,
the following edgecase could occur:

1. some partition is stopped and processed with old version
2. slapos.core is upgraded
3. connection to master is lost
4. offline processing wrongly starts the services of stopped partition

This was because the new version removes the supervisord file for a
partition when the partition is stopped (in online mode) so that the
offline mode can just start all the existing supervisord files. But
since the partitions was never processed in online mode with the new
version, this file was never removed.

To fix this, we use the (now no longer used ) .requested_state file
of the previous version to determine the state of the partition in
offline mode, then we remove both the .requested_state file and the
supervisord file, fixing the discrepancy.