[milo] add weetbix clusters service
[milo] add weetbix clusters service

R=mwarton@google.com, 7f5d2f4f6ce87649784e35ad551490ab8d89e8eb@google.com

Bug: 1337150
Change-Id: I9e89a8e41a56816ce932c66d65cf1f916311baca
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/3706965
Commit-Queue: Tuan Nguyen <7f5d2f4f6ce87649784e35ad551490ab8d89e8eb@google.com>
Auto-Submit: Weiwei Lin <968518a24f41fef00b747498600e52b792d06ae0@google.com>
Reviewed-by: Tuan Nguyen <7f5d2f4f6ce87649784e35ad551490ab8d89e8eb@google.com>

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