Use our local git server instead of cloud.google.com/go,
which may go down or otherwise reject our traffic.
I built and installed git 2.23.0 and confirmed that this
updated test still fails if CL 196961 is rolled back.
So the test is still accurate at detecting the problem.
Change-Id: I58011f6cc62af2f21fbbcc526ba5401f4186eeaf
Reviewed-on: https://go-review.googlesource.com/c/go/+/720322 Reviewed-by: Michael Matloob <matloob@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Matloob <matloob@google.com>