I merged 5cae7c51bfa (removing Notify.BackendLogID) and 93db50356536e
(adding another reference to Notify.BackendLogID) that didn't have merge
conflicts, but didn't compile together.
This removes the new reference, fixing the build.
Updates #14129
Change-Id: I9bb68efd977342ea8822e525d656817235039a66
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>