[Language KCM] Wrap the label text

Summary:
This way the text doesn't get cut off the screen on at least the
PinePhone

Test Plan:
1. Open the Language KCM on a small screen without this patch
2. Open the Language KCM on a small screen with this patch

Reviewers: davidedmundson

Reviewed By: davidedmundson

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D27781