Remove field trial testing config for sync user events

Bug: None
Change-Id: Iafe9077942dd091b0c509c9a4628984883dba15c
Reviewed-on: https://chromium-review.googlesource.com/c/1412492
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: anthonyvd <anthonyvd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623343}
1 file changed