IEditorRegistryTest.testFindExternalEditor test fails

Test didn't considered the fact that there can be multiple editor
descriptors with same id reported by OS, because descriptor id is
nothing else as a program name, which is not unique.

Change-Id: Ib5461ec23881de47db9f00ae869268bd1e0d33ff
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>