Improve error output of integration tests

[stoecker]

The unit tests of external checks are extremely hard to fix, as it is always unclear what they refer to.

Can't they be changed in a way that, so that at least the relevant preset, style, plugin, ... is printed, so that it is clear what file the error messages refer to. E.g. currently presets and styles fail, but I did not find the reason for them.

[Klumbumbus]

I usually search for > KO e.g. at https://josm.openstreetmap.de/jenkins/job/JOSM-Integration/lastCompletedBuild/jdk=JDK8/testReport/org.openstreetmap.josm.gui.preferences.map/TaggingPresetPreferenceTestIT/testValidityOfAvailablePresets/

(However you need to ignore the yopaseopor entries, as they don't let the test fail.)

[Klumbumbus]

The current problem seems to be the <space /> within checkgroup at ​https://raw.githubusercontent.com/ruosm-presets/literan-moscow/master/russian_shops.xml

[Don-vip]

In 12214/josm:

see #14817 - better assertion error message, include preset source url

[Don-vip]

PR created: ​https://github.com/ruosm-presets/literan-moscow/pull/14