Update corpus expectations for MultiplyAlpha() Updates corpus expectations to account for minor alpha differences after reimplementing CFX_SkiaDeviceDriver::MultiplyAlpha() with native Skia operations. Bug: pdfium:1949 Change-Id: I71ceb266922a80c918b0a7ce9733998bd9b6391d Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium_tests/+/105330 Reviewed-by: Nigi <nigi@chromium.org>