[NDM] Add ping metrics to snmp metadata.csv

[ken-schneider]

What does this PR do?

Adds metrics from ping to our metadata.csv so it shows up in our docs.

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

• [ ] Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• [ ] Changelog entries must be created for modifications to shipped code
• [ ] Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• [ ] If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

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Test Results

    6 files    6 suites   24m 2s :stopwatch:   403 tests 403 :white_check_mark:     0 :zzz: 0 :x: 1 881 runs  583 :white_check_mark: 1 298 :zzz: 0 :x:

Results for commit 3b61883f.