Deprecate *.ProtectedPasswordEntry.* histograms

Change-Id: I7ce6db2f85bd0261304935e4f3aa062de51f1783
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1981110
Commit-Queue: Nathan Parker <nparker@chromium.org>
Reviewed-by: Bettina Dea <bdea@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Auto-Submit: Nathan Parker <nparker@chromium.org>
Cr-Commit-Position: refs/heads/master@{#729418}