Re-enable or delete MTE tests

[skaldarnar]

The MTE test was disabled in b5d421d because it was failing on CI.

However, the test seems to work fine when run locally. We should figure out what is going wrong in CI, and this can be fixed.

The following WARN only pops up during CI runs but not locally for me - maybe that gives a clue...

14:34:23.811 [Thread-8] WARN  org.reflections.Reflections - could not create Vfs.Dir from url. ignoring the exception and continuing
    org.reflections.ReflectionsException: could not create Vfs.Dir from url, no matching UrlType was found [file:/home/jenkins/agent/workspace/Terasology_Modules_R_Rails_PR-78/build/resources/test]
    either use fromURL(final URL url, final List<UrlType> urlTypes) or use the static setDefaultURLTypes(final List<UrlType> urlTypes) or addDefaultURLTypes(UrlType urlType) with your specialized UrlType.