Update corpus tests which can be rendered smoothly now

CL [1] modifies the sampling options used for image rendering,
which leads to smoother Skia rendering results for 3 corpus tests.

This CL updates the Skia expectations for these 3 corpus tests.

[1] https://pdfium-review.googlesource.com/96790

Bug: pdfium:1789,pdfium:1859,pdfium:1868
Change-Id: I820b9beedcbcb93cc3e0e3dec5f94040abcbaadb
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium_tests/+/96810
Reviewed-by: Lei Zhang <thestig@chromium.org>