test(sysview_tracing): validate TRACE_STOP per core

conftest.py

@@ -272,6 +272,14 @@ class OpenOCD:
         resp += self.telnet.read_until(b'>')
         return to_str(resp)
 
+    def consume_output(self, duration: float) -> None:
+        if self.telnet is None:
+            return
+        end = time.time() + duration
+        while time.time() < end:
+            self.telnet.read_very_eager()
+            time.sleep(0.05)
+
     def apptrace_wait_stop(self, timeout: int = 30) -> None:
         stopped = False
         end_before = time.time() + timeout