Enable parallel dlt tests

[HiLivin]

Create a dedicated bridge network for each Docker container so that
get_ip()/get_gateway() return addresses unique to that container,
preventing multicast cross-talk between parallel tests.

When a dedicated network is set, get_ip()/get_gateway() default to it.
The first-attached-network fallback is only used when no dedicated
network was provided (e.g. DockerTarget created without a network).

Add a dlt_on_target pytest fixture that uploads dlt-receive to the
target and yields a factory for starting receivers. All receivers are
stopped automatically on teardown.

Suppress two warrnings from third party dlt 2.18.11.

QEMU: Enable logging stderr

[ltekieli]

score/itf/plugins/docker.py:393-401 — Network resource leak on container removal failure

If container.remove(force=True) raises, the exception propagates past the network.remove() block, leaking the Docker network.

Wrapping in an additional finally would guarantee cleanup:

        try:
            try:
                container.stop(timeout=1)
            finally:
                container.remove(force=True)
        finally:
            try:
                network.remove()
            except Exception:
                logger.warning(f"Failed to remove network {network.name}", exc_info=True)