fix(modem): Replace MQTT client with simple ping command

components/esp_modem/examples/pppos_client/pytest_pppos_client.py

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
+# SPDX-FileCopyrightText: 2022-2025 Espressif Systems (Shanghai) CO LTD
 # SPDX-License-Identifier: Unlicense OR CC0-1.0
 from __future__ import print_function, unicode_literals
 
@@ -8,16 +8,12 @@ def test_pppos_connect(dut):
     steps:
       1. initializes connection with SIM800
       2. checks we get an IP
-      3. checks for the MQTT events
+      3. checks that the ping command works
       4. checks that the client cleanly disconnects
     """
     # Check the sequence of connecting, publishing, disconnecting
     dut.expect('Modem Connect to PPP Server', timeout=90)
-    # Check for MQTT connection and the data event
-    dut.expect('MQTT_EVENT_CONNECTED')
-    dut.expect('MQTT_EVENT_DATA')
-    dut.expect('TOPIC=/ci/esp-modem/pppos-client')
-    dut.expect('DATA=esp32-pppos')
+    dut.expect('Ping command finished with return value: 0', timeout=30)
     # Check that we have disconnected
     dut.expect('User interrupted event')
     # And can use commands again