Disable OpenCL support for Windows UWP CI builds Bug: angleproject:5908 Change-Id: I451e232e545248ff9755cc3f2a4907b8af2fdc2c Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2859742 Reviewed-by: Jamie Madill <jmadill@chromium.org> Commit-Queue: John Plate <jplate@google.com>