[v25.3.x] Coordinate transaction end markers removal

[vbotbuildovich]

Backport #29043 to branch v25.3.x. This issue was created as a placeholder because the original PR's commit(s) could not be automatically cherry-picked.
Here are the commands to execute:

git checkout v25.3.x
git checkout -b manual-backport-29043-v25.3.x-124
git cherry-pick -x 1e6bb21e6f be2ab4e6b7 58e7f627ab f0d16fa806 bbd5c5c21d 340be1c0b5 97721dbd75 2260ab0eda 36803febbb 686c8e1782 e96d9cfd66 147f7f61a4 88bcdfb6b5 dc913a2c5b 1cc9bcafc0 7a402429d0 919b22f95d 84e93286e5 c8d6e2354d 1aeb2423a0

git push origin manual-backport-29043-v25.3.x-124
gh pr create \
  --title "[v25.3.x] Coordinate transaction end markers removal" \
  --base "v25.3.x" \
  --label "kind/backport" \
  --head "manual-backport-29043-v25.3.x-124" \
  --draft \
  --repo "redpanda-data/redpanda" \
  --milestone "v25.3.x-next" \
  --body "Backport of PR https://github.com/redpanda-data/redpanda/pull/29043 "