Fix rsyslog configuration for local provider

syslog/config: stop rsyslog breaking for local provider

The rsyslog configuration used to create a default ruleset that dropped all messages after forwarding juju ones onto the state servers. This broke rsyslog for users of the local provider, where the rsyslog configuration was your main machine (all non-juju messages were dropped).

The new config no longer uses a default ruleset. It still forwards juju messages and then only drops the juju ones which have already been handled.

https://bugs.launchpad.net/ubuntu/+source/rsyslog/+bug/479592