Report duration uptime for successful update.

We have metrics for attempt duration, attempt duration uptime and
successful update duration, but not successful update duration uptime,
the existing code already keeps track of this metric, it's just not
being reported, this CL added the last missing piece to report this
metric.

Bug: 77884453
Test: check reported metrics in log
Change-Id: I41d703add2199f54cc6eeb7d92f0d52fc36d9a46