Really use Remote Highlights for nick, not Local

Really use Remote Highlights for nick, not Local

Really disable local nick highlights by default.  This will affect
those who upgrade and haven't changed the default highlight settings.
No settings migration provided since we intend to migrate to
core-side highlights entirely in the future.

Really enable remote nick highlights by default, setting a default
value for when highlights are not yet set up.  Fixes behavior of no
nickname highlighting by default.