We were previously demoing HTTP/1 vs HTTP/2 loading performance using
http:// scheme (which uses HTTP/1 implicitly) on the http2.golang.org
domain for HTTP/1, and https://http2.golang.org for HTTP/2.

But then golang.org got into the HSTS preload list, forcing all
*.golang.org to only be HTTPS.

So now, rather than find a new base domain name, to compare against
HTTP/1 we instead use https://http1.golang.org/ and then use the SNI
name to determine whether we advertise "h2".

Also, some cleanup:

* remove launch.go; it's no longer used since we moved to kubernetes
* use a multi-stage Dockerfile rather than the hacky workarounds
  that used to be necessary to simulate multiple stages
* modernize the kubernetes deployment stuff to match how we do
  it elsewhere ("gcloud docker" is long deprecated too)
* update from Go 1.9 to Go 1.11 for the prod base

Fixes golang/go#30033

Change-Id: I9f6b1f496d4005e5a08bf990843d440005a5b3e8
Reviewed-on: https://go-review.googlesource.com/c/160857Reviewed-by: Andrew Bonventre <andybons@golang.org>