env/windows: more fixes to test_buildlet.bash
env/windows: more fixes to test_buildlet.bash

Fix typo in URL for Go download. Add dummy VERSION to Go repo before
uploading to windows builder.

Updates golang/go#35006

Change-Id: I832aa781884b4da99053bd793909a693900fa937
Reviewed-on: https://go-review.googlesource.com/c/build/+/413414
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@google.com>
Reviewed-by: Carlos Amedee <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@golang.org>
Reviewed-by: Alex Rakoczy <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@golang.org>
Run-TryBot: Than McIntosh <4b2922593166fc595a9b1a408f34f5d3817fe9d2@google.com>

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