timeit: start autorange with 1 iteration, not 10

timeit: start autorange with 1 iteration, not 10

Issue #28240: timeit autorange now uses a single loop iteration if the
benchmark takes less than 10 seconds, instead of 10 iterations.

"python3 -m timeit -s 'import time' 'time.sleep(1)'" now takes 4 seconds
instead of 40 seconds.