Apply enhanced confirmation mode OEM config to Settings

So Settings app will block user accessing restricted settings
if OEM config is off.

Bug: 217709978
Test: With OEM config on, accessibility page for unknown source app is
disabled by default.
Test: With OEM config off, accessibility page for unknown source app is
not disabled.

Change-Id: Id25e8fd76e6192fd4db64f81903449bb02785b39