[release-1.19] fix sub-second precision metric reporting

[knative-prow-robot]

This is an automated cherry-pick of #16358

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.05%. Comparing base (dc9f816) to head (c8cf821).
⚠️ Report is 1 commits behind head on release-1.19.

Additional details and impacted files

@@               Coverage Diff                @@
##           release-1.19   #16360      +/-   ##
================================================
- Coverage         80.11%   80.05%   -0.07%     
================================================
  Files               214      214              
  Lines             13290    13290              
================================================
- Hits              10647    10639       -8     
- Misses             2281     2288       +7     
- Partials            362      363       +1     

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[dprotaso]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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