user_group_pill: Remove unnecessary truthy filter on user_ids.

The filter was not doing anything to the user_id array, not sure why it
was introduced in ce4cf66f3f.

web/src/user_group_pill.ts

@@ -57,7 +57,6 @@ export function get_user_ids(pill_widget: UserGroupPillWidget | CombinedPillCont
     user_ids = [...new Set(user_ids)];
     user_ids.sort((a, b) => a - b);
 
-    user_ids = user_ids.filter(Boolean);
     return user_ids;
 }