[SmartLock] Filter ShowLockScreenToShowFirstStatusToUserDuration metric

Only log to ShowLockScreenToShowFirstStatusToUserDuration.Unlock.Other
if the current SmartLockState indicates that we've successfully
communicated with the phone. If we haven't communicated with the phone,
then the duration to showing the first status is either very short if,
e.g. BT is disabled, or exactly 15 sec if we can't find the phone and
hit the timeout. These cases aren't interesting and only clutter the
histogram.

Bug: b/207090170
Test: Used chrome://histograms to check whether the metric is logged
Change-Id: I652766d9a09da64a52e48dbb703136f73eeea808
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3645096
Reviewed-by: Ryan Hansberry <hansberry@chromium.org>
Reviewed-by: Josh Nohle <nohle@chromium.org>
Commit-Queue: Curt Clemens <cclem@google.com>
Cr-Commit-Position: refs/heads/main@{#1008444}