Revert "Add luci-go tool to be fetched via CIPD"

This reverts commit 3bcc71d83f6d9af93a7408fbea34f6d5f0185c03.

Reason for revert: appears to break official builds due to how the cipd variable is flattened.

Original change's description:
> Add luci-go tool to be fetched via CIPD
>
> Do not remove the adhoc mechanism on GCS that predates CIPD yet, as the recipes
> need to be updated.
>
> Change analyze to not ignore changes to isolate.
>
> R=‚Äčtandrii@chromium.org
>
> Bug: 851596
> Change-Id: Ic068db83dea4c3a0f17b55181de523b16c9838a5
> Reviewed-on: https://chromium-review.googlesource.com/1097623
> Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
> Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
> Reviewed-by: John Budorick <jbudorick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#569688}

TBR=maruel@chromium.org,tandrii@chromium.org,ehmaldonado@chromium.org,jbudorick@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

No-Presubmit: true
Bug: 851596
Change-Id: I3717c6b0ebf68b08908037850d122727e41bf192
Reviewed-on: https://chromium-review.googlesource.com/1112823
Commit-Queue: John Budorick <jbudorick@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#569938}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 0c062061326cd05a1ab884e5b2d6e03e2b79f215
3 files changed