End-to-end tests depend on fixed ports

Most of the end-to-end tests rely on known TCP/IP ports to connect the services being tested. These port numbers will collide when more that one build is being tested at the same time.

If all Aseba target utilities report their ephemeral ports, the e2e scripts can be modified to use them. This will be fastidious.

An alternative would be to systematically run e2e tests in containers, so that every test environment is isolated. Currently e2e testing is only performed on Debian, so this approach wouldn't add any constraints.