client: remove dependency to isolate from cipd.py
client: remove dependency to isolate from cipd.py

Bug: 1253255
Change-Id: I1b90a215da05afa44d2ab0827fb6a5cd18406cf8
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/3283400
Auto-Submit: Takuto Ikuta <71927f930fca81015e0f496c65cd126ab1a692e3@chromium.org>
Commit-Queue: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>
Reviewed-by: Junji Watanabe <aaef61ef98ffea505db831f310be2a0eb8492537@google.com>

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