Keep the old metric and add a new one for Prometheus.
Keep the old metric and add a new one for Prometheus.

Export a value of 1 each time, as that way it's easy to do math, and we
aren't using the enum value anyway.

Signed-off-by: Maggie Zhou <826b1579432fb3d92c18d0aaf5c045d46c2ddd46@slack-corp.com>

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