This test was removed long ago ineb0e3ba.Signed-off-by: Damien George <damien@micropython.org>

The aim of this commit is to make it so that the existing thread tests canbe used to test the _thread module on the rp2 port.  The rp2 port onlyallows up to one thread to be created at a time, and does not have the GILenabled.The following changes have been made:- run-tests.py skips mutation tests on rp2, because there's no GIL.- run-tests.py skips other tests on rp2 that require more than one thread.- The tests stop trying to start a new thread after there is an OSError,  which indicates that the system cannot create more threads.- Some of these tests also now run the test function on the main thread,  not just the spawned threads.- In some tests the output printing is adjusted so it's the same regardless  of how many threads were spawned.- Some time.sleep(1) are replaced with time.sleep(0) to make the tests run  a little faster (finish sooner when the work is done).For the most part the tests are unchanged for existing platforms like esp32and unix.Signed-off-by: Damien George <damien@micropython.org>

The existing thread_sleep1.py test only tests execution, not accuracy, oftime.sleep.  Also the existing test only tests sleep(0) on targets like rp2that can only create a single thread.The new test in this commit checks for timing accuracy on the main threadand one other thread when they run at the same time.Signed-off-by: Damien George <damien@micropython.org>