Fix autocomplete in EE when permissions are sent

In EE, `@users` can be an array at the point where we remove the current
user, because it can do a permissions check on the users for project
mirroring.

Fix this in CE by only using array methods, not AR methods. We can't use
`delete` because that uses `Object#equal?`, which isn't true in this
case.

app/controllers/autocomplete_controller.rb

@@ -18,8 +18,7 @@ class AutocompleteController < ApplicationController
     if params[:search].blank?
       # Include current user if available to filter by "Me"
       if params[:current_user].present? && current_user
-        @users = @users.where.not(id: current_user.id)
-        @users = [current_user, *@users]
+        @users = [current_user, *@users].uniq
       end
 
       if params[:author_id].present?