tests/thread: Use less resources for stress_aes if settrace enabled.

Signed-off-by: Damien George <damien@micropython.org>

tests/thread/stress_aes.py

@@ -267,7 +267,11 @@ def thread_entry(n_loop):
 if __name__ == "__main__":
     import sys
 
-    if sys.platform == "rp2":
+    if hasattr(sys, "settrace"):
+        # Builds with sys.settrace enabled are slow, so make the test short.
+        n_thread = 2
+        n_loop = 2
+    elif sys.platform == "rp2":
         n_thread = 1
         n_loop = 2
     elif sys.platform in ("esp32", "pyboard"):