[editing] Update PositionIteratorTest to dump all state

This patch changes `PositionIteratorTest` to dump all states to avoid
regression for prepeartion of making `PositionIterator` faster.

Bug: 1132412
Change-Id: I61efdbf44daa009952775ce843658b6fefe375fb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4015669
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1069017}