[Code Health] Remove expired OfflinePages histograms

Removing the following histograms: OfflinePages.ConsistencyCheck.Persistent.ExpiredEntryCount, OfflinePages.ConsistencyCheck.Persistent.MissingFileCount, OfflinePages.ConsistencyCheck.Persistent.ReappearedFileCount

Bug: 1384762
Change-Id: I22de00ecb90e25c0a13d5db962836a5915a3585e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4338359


Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
Commit-Queue: Wissem Gamra <wiss@chromium.org>
Reviewed-by: Max Curran <curranmax@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1118224}