Suppress error log when the installer registry key doesn't exist in both hives.
Suppress error log when the installer registry key doesn't exist in both hives.

It's expected that it only exists in one hive, so it's misleading to see
errors in the log for the other hive.

BUG=none
R=bcwhite@chromium.org

Review URL: https://codereview.chromium.org/1884303002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#387476}

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