cq: limit config group name to 40 chars and fix warning.
cq: limit config group name to 40 chars and fix warning.

Previously, warning included incorrect regexp suggesting that
spaces are allowed.

R=qyearsley, yiwzhang

Change-Id: I85c1ffc9d96f8887bc92aab87300638e0eb2a150
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2418578
Auto-Submit: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Reviewed-by: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>
Commit-Queue: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>

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