GTFS-RT alerts as `NO_SERVICE` but no `CANCELLED/DELETED` trip updates

[mmathieum]

We might have to merge information from GTFS alerts & trip updates as some providers might only publish one of the 2 for cancelled trips.
At the very least, find a way to show it in the UI.

GTFS-RT documentation:

When canceling trips over a number of days, producers should provide TripUpdates referencing the given trip_ids and start_dates as CANCELED as well as an Alert with NO_SERVICE referencing the same trip_ids and TimeRange that can be shown to riders explaining the cancellation (e.g., detour).
https://gtfs.org/documentation/realtime/realtime-best-practices/#alert

When canceling trips over a number of days, producers should provide TripUpdates referencing the given trip_ids and start_dates as CANCELED as well as an Alert with NO_SERVICE referencing the same trip_ids and TimeRange that can be shown to riders explaining the cancellation (e.g., detour).
https://gtfs.org/documentation/realtime/realtime-best-practices/#tripupdate

Ex:

• on March 18, 2025 link1 link2, multiple trips cancelled for 🇨🇦 exo Trains 11 Vaudreuil/Hudson: only NO_SERVICE GTFS-RT alert published not GTFS-RT trip updates... (can see GTFS-RT vehicle on map 🤯 )

Related:

• POI (& Schedule) screen > schedule (times) > show service updates UI ⚠️ ℹ️ mtransit-for-android#157