fix(modem): Make MQTT public broker endpoint configurable

Author: david-cermak

.github/workflows/modem__target-test.yml

@@ -36,6 +36,7 @@ jobs:
         shell: bash
         working-directory: ${{ env.TEST_DIR }}
         run: |
+          . ${GITHUB_WORKSPACE}/ci/config_env.sh
           . ${IDF_PATH}/export.sh
           rm -rf sdkconfig build
           [ -f ${SDKCONFIG} ] && cp ${SDKCONFIG} sdkconfig.defaults

components/esp_modem/examples/pppos_client/sdkconfig.ci.sim800_c3

@@ -15,3 +15,4 @@ CONFIG_EXAMPLE_PAUSE_NETIF_TO_CHECK_SIGNAL=y
 CONFIG_ESP_SYSTEM_PANIC_PRINT_HALT=y
 CONFIG_ESP32_PANIC_PRINT_HALT=y
 CONFIG_EXAMPLE_DETECT_MODE_BEFORE_CONNECT=y
+CONFIG_EXAMPLE_MQTT_BROKER_URI="mqtt://${CI_MQTT_BROKER_URI}"

components/esp_modem/examples/pppos_client/sdkconfig.ci.usb_a7670_s2

@@ -12,3 +12,4 @@ CONFIG_EXAMPLE_MODEM_PPP_AUTH_NONE=y
 CONFIG_EXAMPLE_MQTT_TEST_TOPIC="/ci/esp-modem/pppos-client"
 CONFIG_ESP_SYSTEM_PANIC_PRINT_HALT=y
 CONFIG_ESP32_PANIC_PRINT_HALT=y
+CONFIG_EXAMPLE_MQTT_BROKER_URI="mqtt://${CI_MQTT_BROKER_URI}"

components/esp_modem/examples/simple_cmux_client/sdkconfig.ci.sim800_cmux

@@ -16,4 +16,4 @@ CONFIG_COMPILER_CXX_EXCEPTIONS=y
 CONFIG_ESP_MAIN_TASK_STACK_SIZE=8192
 CONFIG_EXAMPLE_CLOSE_CMUX_AT_END=y
 CONFIG_EXAMPLE_MQTT_TEST_TOPIC="/ci/esp-modem/pppos-client"
-CONFIG_BROKER_URI="mqtt://test.mosquitto.org"
+CONFIG_BROKER_URI="mqtt://${CI_MQTT_BROKER_URI}"