Mission system test fails intermittently

[julianoes]

Looks like some race condition:

 [ RUN      ] SystemTest.MissionRawUpload
[02:24:23|Info ] MAVSDK version: v3.10.2-78-gb26d20f7 (mavsdk_impl.cpp:33)
[02:24:23|Info ] MAVSDK version: v3.10.2-78-gb26d20f7 (mavsdk_impl.cpp:33)
[02:24:23|Info ] New system on: 127.0.0.1:52579 (with system ID: 1) (udp_connection.cpp:263)
[02:24:23|Debug] New system ID: 1 Comp ID: 1 (mavsdk_impl.cpp:1063)
[02:24:23|Debug] Verbose component metadata logging is on (mavlink_component_metadata.cpp:27)
[02:24:23|Debug] Component Autopilot (1) added. (system_impl.cpp:487)
[02:24:23|Debug] Discovered 1 component(s) (system_impl.cpp:607)
[02:24:23|Debug] New system ID: 245 Comp ID: 190 (mavsdk_impl.cpp:1063)
[02:24:23|Debug] Verbose component metadata logging is on (mavlink_component_metadata.cpp:27)
[02:24:23|Debug] Component Ground station (190) added. (system_impl.cpp:487)
[02:24:23|Debug] Discovered 1 component(s) (system_impl.cpp:607)
[02:24:23|Error] Int messages are not supported. (mavlink_mission_transfer_client.cpp:38)
/Users/runner/work/MAVSDK/MAVSDK/src/system_tests/mission_raw_upload.cpp:42: Failure
Expected equality of these values:
  mission_raw.upload_mission(result_pair.second.mission_items)
    Which is: Int Messages Not Supported
  MissionRaw::Result::Success
    Which is: Success

[  FAILED  ] SystemTest.MissionRawUpload

Seen in https://github.com/mavlink/MAVSDK/actions/runs/19055140545/job/54423634577?pr=2682.