Update the "os" dimension of Windows tasks to Windows-19041.

This is a cherry-pick of https://skia-review.googlesource.com/c/skia/+/418316/ onto android/next-release.

Change-Id: Ibab9cabddf922bf1c430a623e0a535066aa10835
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/418796
Commit-Queue: Leandro Lovisolo <lovisolo@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
Auto-Submit: Leandro Lovisolo <lovisolo@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
2 files changed