Clean RabbitMQ (delete all the exchanges and queues) before and after running tests

Update `test` Makefile target to clean the RabbitMQ exchanges before and after running the tests.

This way tests don't pollute exchanges which are also used by the devenv.

Note: This is a short term solution. Long term and better solution would be to use different exchanges for tests.

Or even better, split the tests into functional and integration tests (functional tests shouldn't require any service to run).