Update expiration of K-anonymity histograms

Fixed: 1384031
Change-Id: I0dbc9ae029fc944fd1242e764d1bc8c5af44350a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4027427


Commit-Queue: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Russ Hamilton <behamilton@google.com>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Auto-Submit: Russ Hamilton <behamilton@google.com>
Cr-Commit-Position: refs/heads/main@{#1072305}