Send Metrics data as non-durable

[bording]

For transports that support non-durable messages (which at this point is only RabbitMQ), there can be performance advantages for sending messages as non-durable.

Metrics data seems like a good candidate for this kind of optimization because each individual data point isn't business critical.

For RabbitMQ, if we sent metrics data as non-durable, it gives the broker permission to skip disk I/O.