Make the string translatable

Summary:
Currently this string is marked as untranslatable for the unknown reason

Patch by Victor Ryzhykh

Test Plan: Translate, run.

Reviewers: #kwin, zzag

Reviewed By: #kwin, zzag

Subscribers: kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D29271

kcmkwin/kwinoptions/focus.ui

@@ -226,7 +226,7 @@
         </size>
        </property>
        <property name="text">
-        <string notr="true">Window activation policy description</string>
+        <string>Window activation policy description</string>
        </property>
        <property name="alignment">
         <set>Qt::AlignLeading|Qt::AlignLeft|Qt::AlignTop</set>