[Analysis] Grant LUCI services access to read buildbucket builds.
[Analysis] Grant LUCI services access to read buildbucket builds.

And their ResultDB invocations. Needed for LUCI Analysis ingestion
to migrate to project-scoped authentication.

BUG=b:258980021
TEST=None

Change-Id: I130b36a12ddcee17e1a2938882750ef28f069013
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/4022069
Commit-Queue: Patrick Meiring <496ae7b7898d641db15cbb7f3340e9390316ae10@google.com>
Reviewed-by: Vadim Shtayura <9f116ddb1b24f6fc1916a676eb17161b6c07dfc1@chromium.org>

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py