[graphite] Move lingering Viewer flag handling to SetTestOptions

Bug: b/362718561
Change-Id: I230ed94333e13e9c0481e41ac8ac4d83decaa090
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/897099
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
9 files changed