Re-enable _multi_device in test_examples

[ordabayevy]

Removed _multi_device because of the error below (with TEST_DEVICES=2) which I could not get fixed

RuntimeError: The server socket has failed to listen on any local network address. The server socket has failed to bind to [::]:42063 (errno: 98 - Address already in use). The server socket has failed to bind to 0.0.0.0:42063 (errno: 98 - Address already in use).

Strangely this only happens when running all multi device tests (pytest -k multi_device) but doesn't happen when I run only test_examples (pytest test/test_examaples.py).

Originally posted by @ordabayevy in #42 (comment)