tests/kernel/queue: Mark SMP-unsafe case 1cpu, reduce logging output

The test_queue_multithread_competition case wants to be sure that an
inserted item is recevied by the highest priority thread of several
waiting, but that only works if the threads aren't racing against each
other on different CPUs.

Also, the test_queue_loop case would produce a LOT of console output
very quickly.  On a few occasions, I saw this overflow the 8k output
buffer of the intel_adsp devices at exactly the wrong time (with
respect to the polling loop in the host python script), cause a flush
of the stream, and then miss the SUCCESSFUL message.  Quiet things
down a bit, there's not a lot of value of verbosity in a CI test.

Signed-off-by: Andy Ross <andrew.j.ross@intel.com>