Backport of Don't show English strings to the user

Original commit:

commit 1b49ea4d3154630f79b604a191265cff687c18ad
Author: Albert Astals Cid <aacid@kde.org>
Date: Wed Apr 17 00:07:07 2019 +0200

KKeySequenceWidget: Don't show English strings to the user

Summary:
KKeyServer::modToStringUser is only for english texts