Revert "[infra] Update checked-in SDK to 2.17.0-266.1.beta"

This reverts commit bf2c56afbf.

Reason for revert: skia dart->engine autoroller still uses `pub`, which is removed in this update

Original change's description:
> [infra] Update checked-in SDK to 2.17.0-266.1.beta
>
> Bug: https://github.com/dart-lang/sdk/issues/48818
> Change-Id: Ic0658c7b60f12911f974f6580b3e378569b509c1
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/241516
> Auto-Submit: Alexander Thomas <athom@google.com>
> Reviewed-by: William Hesse <whesse@google.com>
> Commit-Queue: William Hesse <whesse@google.com>

TBR=whesse@google.com,athom@google.com

Change-Id: Ibf5c8a277b900c05d917d9b765f38252edb968b9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/dart-lang/sdk/issues/48818
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/241684
Reviewed-by: Alexander Aprelev <aam@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Alexander Aprelev <aam@google.com>

DEPS

@@ -39,7 +39,7 @@ vars = {
 
   # Checked-in SDK version. The checked-in SDK is a Dart SDK distribution in a
   # cipd package used to run Dart scripts in the build and test infrastructure.
-  "sdk_tag": "version:2.17.0-266.1.beta",
+  "sdk_tag": "version:2.16.2",
 
   # co19 is a cipd package. Use update.sh in tests/co19[_2] to update these
   # hashes. It requires access to the dart-build-access group, which EngProd