tests/run-tests.py: Enable -X realtime option for macOS tests.

This enables the new `-X realtime` runtime option when running tests on
macOS.  This causes MicroPython to configure all threads to be high
priority so that they are allowed to use high precision timers.  This
makes tests that depend on the passage of time more likely to succeed.

CI tests that were disabled because of this are now enabled again.

Signed-off-by: David Lechner <david@pybricks.com>

tests/run-tests.py

@@ -258,6 +258,8 @@ def run_micropython(pyb, args, test_file, is_special=False):
             cmdlist = [MICROPYTHON, "-X", "emit=" + args.emit]
             if args.heapsize is not None:
                 cmdlist.extend(["-X", "heapsize=" + args.heapsize])
+            if sys.platform == "darwin":
+                cmdlist.extend(["-X", "realtime"])
 
             # if running via .mpy, first compile the .py file
             if args.via_mpy: