Revert "[config_service] cache compressed config value."
Revert "[config_service] cache compressed config value."

This reverts commit 8d10661b8e70a3efeb518dfee951ddcfdd12dbcf.

Reason for revert: unintentional s/set/add.

Original change's description:
> [config_service] cache compressed config value.
> 
> Quickfix for Milo config being >1 MiB in chromium.
> 
> R=​vadimsh@chromium.org
> 
> Change-Id: Icce4d450abf4633c89fc62b25215d3d3aba55af9
> Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/2135345
> Auto-Submit: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
> Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
> Reviewed-by: smut <smut@google.com>
> Commit-Queue: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>

TBR=iannucci@chromium.org,vadimsh@chromium.org,smut@google.com,a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com,infra-scoped@luci-project-accounts.iam.gserviceaccount.com

Change-Id: Ie471a9774da942513835d20d5e23d08617c153c4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-py/+/2136082
Reviewed-by: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>
Commit-Queue: Andrii Shyshkalov <a30c74fa30536fe7ea81ed6dec202e35e149e1fd@google.com>

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