[desktoppackage] Re-add spacing between inline message and first UI element

Summary:
This patch fixes the lack of spacing between the inline message that shows up when widgets and locked and the first UI element present in the layout.

Included is also one minor wrong title case fix.

BUG: 408712

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D21810