Address request from project-chip#10771

There was a request to add a timeout to the join in project-chip#10771.
The thread itself is unlikely to hang - more likely situation here
is the subscription failing to cause updates, causing the main
thread to hang forever on the condition variable. Added time outs
to both so we can have a bit more information about what actually
happened when the test completes.

src/controller/python/test/test_scripts/base.py

@@ -370,10 +370,21 @@ def run(self):
             changeThread.start()
             with handler.cv:
                 while handler.subscriptionReceived < 5:
-                    # We should observe 10 attribute changes
-                    handler.cv.wait()
-            changeThread.join()
-            return True
+                    # We should observe 5 attribute changes
+                    # The changing thread will change the value after 3 seconds. If we're waiting more than 10, assume something
+                    # is really wrong and bail out here with some information.
+                    if not handler.cv.wait(10.0):
+                        self.logger.error(f"Failed to receive subscription update")
+                        break
+
+            # thread changes 5 times, and sleeps for 3 seconds in between. Add an additional 3 seconds of slack. Timeout is in seconds.
+            changeThread.join(18.0)
+            if changeThread.is_alive():
+                # Thread join timed out
+                self.logger.error(f"Failed to join change thread")
+                return False
+            return True if handler.subscriptionReceived == 5 else False
+
         except Exception as ex:
             self.logger.exception(f"Failed to finish API test: {ex}")
             return False