increase maximum threads, and attempt to avoid running servers on the
same port in the same vm
rework the concurrency test so that the count down latch should close
before timeout

if it doesn't, then the test will still fail, but if it does, then we
can debug how many threads completed
add debug message when returning from upload artifact for logging
purposes
temporarily increase restlet debugging to trace
add counts to verify how many threads started, as this may be more
useful than checking how many ended for debugging
make concurrency test work for 9 threads