Autodisable preference

Authored by Krenair.


Autodisable preference

We want to flip the default of visualeditor-enable to true, but don't
necessarily want to turn it on for users who already have contributions but who
haven't already enabled it. Therefore we're considering adding such users to
this autodisable preference which they can self-remove (by explicitly enabling
VE) or we can target later, separate from betatempdisable users.

Bug: T112352
Change-Id: I1ce5e6c92055e30fdc82bc912a767e913b190ef6