Improve flicker when enter Security page

The flicker preferences are injected from external apps and the text
shifting is due to it needing time to load the icon from the content
uri. To avoid flicker, put a transparent icon as default to wait for
icon update.

Fixes: 189165518
Test: robotests & visual
Change-Id: I727eeefd5455711a53d3fd9ccd5356a15b9daae4