[sync] Remove Sync.ModelTypeRedundantPut

The histogram has collected sufficient data already.

Change-Id: I5aeec8038cb25b301d4cee7b86143a2b84dede6a
Bug: 1130649
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2435112


Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812007}