gddo-server: remove RedirectHost field from gddoEvent With golang.org/cl/242097, the teeproxy no longer needs the RedirectHost field from gddoEvent. Change-Id: Iaf1647d7939084b2bf2d41816d259c7c274283dc Reviewed-on: https://go-review.googlesource.com/c/gddo/+/242098 Reviewed-by: Jonathan Amsterdam <jba@google.com>