[cv][gerrit] reduce noise from misconfigured Gerrit hosts.
[cv][gerrit] reduce noise from misconfigured Gerrit hosts.

This is fragile, but the only purpose is to reduce the noise,
not correctness of error code.

R=yiwzhang

Change-Id: I68a8d13597447e4c5cc2beea6a9d6a6922ffcce2
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2998704
Auto-Submit: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Commit-Queue: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>
Reviewed-by: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go