tests/extmod/asyncio_threadsafeflag.py: Update for unix select.

1. Remove the skip for detecting support for polling user-defined objects
   as this is always possible now on all ports.
2. Don't print when the scheduled task runs as the ordering of this
   relative to the other prints is dependent on other factors (e.g. if
   using the native emitter).

This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

tests/extmod/asyncio_threadsafeflag.py

@@ -16,17 +16,6 @@ except AttributeError:
     raise SystemExit
 
 
-try:
-    # Unix port can't select/poll on user-defined types.
-    import select
-
-    poller = select.poll()
-    poller.register(asyncio.ThreadSafeFlag())
-except TypeError:
-    print("SKIP")
-    raise SystemExit
-
-
 async def task(id, flag):
     print("task", id)
     await flag.wait()
@@ -34,9 +23,7 @@ async def task(id, flag):
 
 
 def set_from_schedule(flag):
-    print("schedule")
     flag.set()
-    print("schedule done")
 
 
 async def main():

tests/extmod/asyncio_threadsafeflag.py.exp

@@ -9,8 +9,6 @@ yield
 task 2
 set event
 yield
-schedule
-schedule done
 wait task
 task 2 done
 ----