This reverts commit eebc3d82.

Reason for revert: crbug.com/874586

Original change's description:
> [cipd] Check CIPD client hash against pinned SHA256 during updates.
> 
> Linux and OSX only for now. This also rolls CIPD client to a version that
> supports pinned hashes (v2.2.5).
> 
> CIPD_CLIENT_VER and CIPD_CLIENT_SRV are no longer supported as env vars, since
> it makes no sense when pinning hashes of the binaries at specific version on
> the specific backend.
> 
> Also somewhat cleanup 'cipd' script to use "${VAR}", stderr and colored output
> consistently.
> 
> R=​iannucci@chromium.org, nodir@chromium.org
> BUG=870166
> 
> Change-Id: I9e61f9f8fbdcf10985c52828b2bfbec64b4234f0
> Reviewed-on: https://chromium-review.googlesource.com/1171957
> Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>
> Reviewed-by: Nodir Turakulov <nodir@chromium.org>

TBR=iannucci@chromium.org,vadimsh@chromium.org,nodir@chromium.org

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

Bug: 870166
Change-Id: I9aa8e7a7f07520aa69d366c76e4dbccae345bc00
Reviewed-on: https://chromium-review.googlesource.com/1175294Reviewed-by: Vadim Shtayura <vadimsh@chromium.org>
Commit-Queue: Vadim Shtayura <vadimsh@chromium.org>