CI: improve mavros SITL tests logging (#8714)

* add more logging to help with #8556
* log subscribed topics on mission start and test exit (pass or fail)
* use mavlink enums everywhere to avoid maintaining dictionary mappings and to have readable values
* log when the FCU advances to next mission item without satisfying the position reached offset/radius
* some renaming for readability
* log more state value changes (connected and MAV_STATUS)