Remove "teaser-dropbox-text" experiment

services/web/public/coffee/main/account-upgrade.coffee

@@ -19,13 +19,7 @@ define [
 						url = "#{url}&cc=#{couponCode}"
 				$scope.startedFreeTrial = true
 
-				switch source
-					when "dropbox"
-						sixpack.participate 'teaser-dropbox-text', ['default', 'dropbox-focused'], (variant) ->
-							event_tracking.sendMB "subscription-start-trial", { source, plan, variant }
-
-					else
-						event_tracking.sendMB "subscription-start-trial", { source, plan }
+				event_tracking.sendMB "subscription-start-trial", { source, plan }
 
 				w.location = url