[v23.3.x] Metrics for transform logging

[vbotbuildovich]

Backport #16566 to branch v23.3.x. Note that this issue was created as a placeholder, since the original PR's commit(s) could not be automatically cherry-picked.
Here are the commands to execute:

git checkout v23.3.x
git checkout -b vbotbuildovich/backport-16566-v23.3.x-28
git cherry-pick -x c31ea7f3c9adcc395e7b025dbd3c71d0c916a491 6d59f927053f8117bc14bddf273ef4b15773c3c1 b3a663798f0ce6c14d20805251ca3aa20316e808

git push origin vbotbuildovich/backport-16566-v23.3.x-28
gh pr create \
  --title "[v23.3.x] Metrics for transform logging" \
  --base "v23.3.x" \
  --label "kind/backport" \
  --head "vbotbuildovich/backport-16566-v23.3.x-28" \
  --draft \
  --repo "redpanda-data/redpanda" \
  --milestone "v23.3.x-next" \
  --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/16566 "