[System Tray] Fix regression on SNI fallback

As mentioned in https://bugs.kde.org/show_bug.cgi?id=365308
because of 27b103075600 we regressed on 5d5518455d10.

This patch fixes it again.

Reviewers: Plasma, broulik, davidedmundson, mart

Reviewed By: mart

Subscribers: plasma-devel

Tags: Plasma

Differential Revision: https://phabricator.kde.org/D5270