Improve handling of SIRI added trip with unresolvable agency

[vpaturet]

Summary

When creating an extra-journey, the SIRI updater attempts to resolve the agency to which the trip belongs.
The algorithm does not always succeed in finding the agency. When it fails, it leads to a NullPointerException:

Adding EstimatedJourney EstimatedVehicleJourney{EstimatedVehicleJourneyCode: 'TRO:ServiceJourney:26_240524122635892_1084:3510509093', Operator: TRO:Operator:960, Line: TRO:Line:1_26} failed.
java.lang.NullPointerException: null
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at org.opentripplanner.transit.model.network.Route.<init>(Route.java:46)
	at org.opentripplanner.transit.model.network.RouteBuilder.buildFromValues(RouteBuilder.java:215)
	at org.opentripplanner.transit.model.network.RouteBuilder.buildFromValues(RouteBuilder.java:14)
	at org.opentripplanner.transit.model.framework.AbstractBuilder.build(AbstractBuilder.java:33)
	at org.opentripplanner.ext.siri.AddedTripBuilder.createRoute(AddedTripBuilder.java:308)
	at org.opentripplanner.ext.siri.AddedTripBuilder.build(AddedTripBuilder.java:175)
	at org.opentripplanner.ext.siri.SiriTimetableSnapshotSource.apply(SiriTimetableSnapshotSource.java:154)
	at org.opentripplanner.ext.siri.SiriTimetableSnapshotSource.lambda$applyEstimatedTimetable$1(SiriTimetableSnapshotSource.java:118)
	at org.opentripplanner.updater.trip.TimetableSnapshotManager.withLock(TimetableSnapshotManager.java:218)
	at org.opentripplanner.ext.siri.SiriTimetableSnapshotSource.applyEstimatedTimetable(SiriTimetableSnapshotSource.java:107)
	at org.opentripplanner.ext.siri.updater.EstimatedTimetableHandler.applyUpdate(EstimatedTimetableHandler.java:61)
	at org.opentripplanner.ext.siri.updater.AsyncEstimatedTimetableProcessor.lambda$processSiriData$0(AsyncEstimatedTimetableProcessor.java:38)
	at org.opentripplanner.updater.GraphUpdaterManager.lambda$execute$1(GraphUpdaterManager.java:192)

This PR handles this corner case by reporting a specific error message in this case.
(This will allow further analysis by reviewing error log messages)

Issue

No

Unit tests

Added unit test

Documentation

No

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.45%. Comparing base (ce93c85) to head (d0ec77e).
Report is 2 commits behind head on dev-2.x.

Additional details and impacted files

@@            Coverage Diff             @@
##             dev-2.x    #5931   +/-   ##
==========================================
  Coverage      69.45%   69.45%           
- Complexity     17065    17072    +7     
==========================================
  Files           1934     1934           
  Lines          73624    73628    +4     
  Branches        7539     7540    +1     
==========================================
+ Hits           51134    51140    +6     
+ Misses         19866    19864    -2     
  Partials        2624     2624           

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[vpaturet]

@lassetyr we apply today some complex logic to "guess" the agency of an extra journey when its line or replaced line cannot be resolved.
Should extra journeys that do not refer to an existing line or existing replaced line simply be discarded?
What are the requirements in the Nordic SIRI profile?

[t2gran]

The code changes look ok, I have not looked at the business logic.