Remove PersistedTabData maintenance flag

It was launched to 100% in price tracking with no issues identified

Bug: 1294366
Change-Id: I3fc714db26c6cc1ff72060b4b93953bd0d760bc7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3440918


Reviewed-by: Ayman Almadhoun <ayman@chromium.org>
Reviewed-by: David Maunder <davidjm@chromium.org>
Commit-Queue: David Maunder <davidjm@chromium.org>
Cr-Commit-Position: refs/heads/main@{#968366}