Point k8s-checker to k8s-config main ref
Point k8s-checker to k8s-config main ref

Bug: skia:12036
Change-Id: Ib1e22f6d5227263b7bfb29a603d03a0a997defd3
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/411862
Reviewed-by: Eric Boren <0e499112533c8544f0505ea0d08394fb5ad7d8fa@google.com>
Commit-Queue: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot