Initialize injected Security preferences.

Previously a default "G" icon was loaded before the injected ones and
this would be visually jarring. Also the text summary would cause the
titles to shift up, so now load an empty icon and empty summary so no
more jarring visual effects.

Bug: 35994047
Test: make RunSettingsRoboTests
Change-Id: Ia06535215432fe350a3bb06f541e817a566772e0