Change default mvd to v20a_tr
Following https://redmine.cbm.gsi.de/issues/2119 and SWM discussion, recommended MVD version "v20c_tr" was not compatible with sts "v19a". This change should be reverted once a new STS geometry is available.
Following https://redmine.cbm.gsi.de/issues/2119 and SWM discussion, recommended MVD version "v20c_tr" was not compatible with sts "v19a". This change should be reverted once a new STS geometry is available.