Update expiry of ManagedUsers.* histograms

Bug: 1088894
Change-Id: I9b84e130df9b72ef00d37e50d993c8313bcf5d50
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2315923


Reviewed-by: Yilkal Abe <yilkal@chromium.org>
Reviewed-by: Alex Ilin <alexilin@chromium.org>
Commit-Queue: Aga Wronska <agawronska@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791495}