Comment 0 for bug 1904874

When routers are migrated from one Neutron agent to the other, the metering IPtables
rules are removed, which can cause some exceptions that can be ignored. The metering
agent already handled this situation. However, it logs the message as an ERROR, which
can triggers alarms in the cloud monitoring systems.

The message is imported to be logged. However, we should change it to warning, instead
of error. Normally, in complex cloud environments, people configure alarms to be triggered
whenever an error message appears, and operators have to act upon it. These messages can trigger
such situations, which are misleading. Therefore, we propose here to change the LOG message from error to warning.