[milo] Modernize OWNERS a bit.
[milo] Modernize OWNERS a bit.

The 4 current entries are either not working on Milo, or are not
in ChOps at all any more :)

R=jsca@google.com, 968518a24f41fef00b747498600e52b792d06ae0@google.com

Change-Id: I29cd4d383629efb45a01e9ee91161475f0e576e3
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2042770
Auto-Submit: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Reviewed-by: Weiwei Lin <968518a24f41fef00b747498600e52b792d06ae0@google.com>
Commit-Queue: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>

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