MediaWiki theme: Remove unnecessary OptionWiget `border` property
MediaWiki theme: Remove unnecessary OptionWiget `border` property

It's never applied and therefore not necessary to reset.

Change-Id: I07d11b87f006977d195f50fe54344ffbd876524a

wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui,wikimedia/oojs-ui