Update PagePosition corpus expectations

As a result of https://pdfium-review.googlesource.com/115811 changing
how font metrics are calculated, the differences in rounding causes some
PDFs to render slightly differently.

Change-Id: I46007b35db236a9e0d4355dd6404e044691e9388
Reviewed-on: https://pdfium-review.googlesource.com/c/pdfium_tests/+/115910
Reviewed-by: Dominik Röttsches <drott@chromium.org>