For all transport errors, we first got a log of a failure with a
backtrace like 'Fail to publish message on topic' or 'fail to consume
messages' and then another message like 'AMQP is unreachable'.
But in most case, we retry to consume/publish messages when the reason
is a connection lost.
So, now we don't log the failure message anymore in case of connection lost,
but just message related to rabbit deconnection/reconnection.
The error message and the backtrace are only logged in case of we really fail to
publish a message.
Change-Id: Ifa1b04b348b347bad0b2abec3e759a2ce7815b86
2d1a019427