[logdog] Assume datastore is available in collector/archivist.
[logdog] Assume datastore is available in collector/archivist.

It is. Also the mode when it isn't probably has rotten away long
time ago.

R=40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org, 50b2a565e2e78c292794832469a30ce5abc9959c@google.com
BUG=1090916

Change-Id: Ib1a6e4f9028970d15eedec136aebd778b9693ff9
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2246262
Reviewed-by: Robbie Iannucci <40f3d43a28ebae3cb819288542e1c84d73d962d5@chromium.org>
Reviewed-by: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>
Commit-Queue: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>

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