[milo] Make all partial milo URLs serve or redirect.
[milo] Make all partial milo URLs serve or redirect.

Bug:
Change-Id: Iadb93e0d0b323c8cfec5d5caf61f1acc7034ac50
Reviewed-on: https://chromium-review.googlesource.com/758703
Reviewed-by: Ryan Tseng <2190fe9a39b4920ec7bd59c848ec5cccd163056f@chromium.org>
Commit-Queue: Erik Staab <9e0728822fdb2ce07b011b42510312bb837e6a51@chromium.org>

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