Demote network pool batch size logs to debug

[mrmr1993]

As requested by @lk86, this PR demotes the noisy network pool batcher logs from info to debug, to help clean up the daemon log output.

Checklist:

• Modified the current draft of release notes with details on what is completed or incomplete within this project
• Document code purpose, how to use it
  • Mention expected invariants, implicit constraints
• Tests were added for the new behavior
  • Document test purpose, significance of failures
  • Test names should reflect their purpose
• All tests pass (CI will check this if you didn't)
• Serialized types are in stable-versioned modules
• Does this close issues? List them

[mrmr1993]

!ci-build-me

[nholland94]

These almost could even be "spam" level logs. But debug works well too.

[lk86]

!ci-build-me