Hide the SelfAvailablePreference if it is not available.

- instead of removing it from the preference screen, set its visibility
to false, so that if it becomes available later, it will still be found
on the screen.

Bug: 119838520
Test: make RunSettingsRoboTests
Change-Id: Idc7079bb5846aef247dd87c0b0dba2546f2d8f8f