Fix warning on deprecated ROS release notes. (backport #6907)

[mergify]

Description

@keithkirkwood-3di at 3Di is reporting a new warning that is blocking them. I don't have a good sense of the root cause of the warning but the offending line doesn't seem like it is necessary and the warning only appears on deprecated releases so I am pretty sure it can be safely removed.

Fixes # (issue)

Did you use Generative AI?

No.

Additional Information

If this doesn't work feel free to close the PR.

---

This is an automatic backport of pull request #6907 done by Mergify.

[mergify]

Cherry-pick of 1a70bf8 has failed:

On branch mergify/bp/kilted/pr-6907
Your branch is up to date with 'origin/kilted'.

You are currently cherry-picking commit 1a70bf8.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   source/Releases/Release-Dashing-Diademata.rst
	modified:   source/Releases/Release-Eloquent-Elusor.rst
	modified:   source/Releases/Release-Foxy-Fitzroy.rst

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   conf.py

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[github-actions]

HTML artifacts: https://github.com/ros2/ros2_documentation/actions/runs/27939498392/artifacts/7787036301.

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