Revert "[infra] Temporarily mark CQ Windows SDK builder as experimental"
Revert "[infra] Temporarily mark CQ Windows SDK builder as experimental"

This reverts commit 3493aae5123a8429428877131516b25012d6e391.

Reason for revert: The Windows bots have access to the VS toolchain again.
https://bugs.chromium.org/p/chromium/issues/detail?id=812927

Original change's description:
> [infra] Temporarily mark CQ Windows SDK builder as experimental
> 
> TBR=whesse@google.com
> 
> Change-Id: I95042b0ec8cb056ef2a825ba81c5258c0789df7c
> Reviewed-on: https://dart-review.googlesource.com/41821
> Reviewed-by: Alexander Thomas <29642742b6693024c89de8232f2e2542cf7eedf7@google.com>

TBR=whesse@google.com,29642742b6693024c89de8232f2e2542cf7eedf7@google.com

Change-Id: I2f064b40536fd771d0b87aa4756f9596ccaace76
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/41980
Reviewed-by: Alexander Thomas <29642742b6693024c89de8232f2e2542cf7eedf7@google.com>
Commit-Queue: Alexander Thomas <29642742b6693024c89de8232f2e2542cf7eedf7@google.com>

dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk