Don't check if the job exists if we are going to ignore the result

[JENKINS-15747] Improved fix: not only cap total number of transitive upstream causes but also avoid redundantly storing information about upstream causes listed elsewhere.

Now that we're lazy loading builds, calling getBuildByNumber is not cheap.
So evaluate the 'ignore' flag before trying to load the build.

JENKINS-16573 Getting testing result from non default test mojo failed build.

Observed in a log from 1.466.x:
… hudson.model.Run run
SEVERE: Failed to rotate log
java.io.IOException: …/builds/2013-… is in use
	at hudson.model.Run.delete(Run.java:1260)
	at hudson.model.AbstractBuild.delete(AbstractBuild.java:387)
	at hudson.tasks.LogRotator.perform(LogRotator.java:157)
	at hudson.model.Job.logRotate(Job.java:337)
	at hudson.model.Run.run(Run.java:1503)
	…

Fix French and Danish translations for core update
Thanks

Removed old and outdated todo.txt

This was lost in 0f2737f8

While several plugins implemented the interface under the old name, only core was checkcasting it.