cmd/buildlet: update vcs-test.golang.org IP
cmd/buildlet: update vcs-test.golang.org IP

It's changing as part of the move to GKE.

Keep the old IP temporarily accessible
while the DNS change gradually propagates.

For golang/go#53889.
Updates golang/go#51444.

Change-Id: I324623c3b79d1b7af0dd2d8f3aea5acec4b849f7
Reviewed-on: https://go-review.googlesource.com/c/build/+/418777
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@google.com>
Auto-Submit: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

golang/build,golang/build,golang/build,golang/build