[20694] Build Fast DDS Python bindings in Fast DDS Docs Github CI job (backport #4628)

[mergify]

Description

This PR extends the ubuntu-build-and-test-documentation Github CI job to include Fast DDS Python in the build.
It also uses a new action from eProsima-CI to deduce which branch to use:

• [20694] Add Ubuntu get_related_branch_from_repo eProsima-CI#82

TODO:

• Drop the commit Refs #20694: DROP Run docs CI even when skip-ci that is added to ease reviewing the PR
• Pin used version of get_related_branch_from_repo once eProsima-CI releases the new action

@Mergifyio backport 2.13.x 2.10.x 2.6.x

Contributor Checklist

• Commit messages follow the project guidelines.

• The code follows the style guidelines of this project.

• N/A: Tests that thoroughly check the new feature have been added/Regression tests checking the bug and its fix have been added; the added tests pass locally

• N/A: Any new/modified methods have been properly documented using Doxygen.

• N/A: Changes are ABI compatible.

• N/A: Changes are API compatible.

• N/A: New feature has been added to the versions.md file (if applicable).

• N/A: New feature has been documented/Current behavior is correctly described in the documentation.

• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.

---

This is an automatic backport of pull request #4628 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of decf689 has failed:

On branch mergify/bp/2.6.x/pr-4628
Your branch is up to date with 'origin/2.6.x'.

You are currently cherry-picking commit decf68986.
  (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)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .github/workflows/documentation-tests.yaml

no changes added to commit (use "git add" and/or "git commit -a")

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

[Mario-DL]

@EduPonz would you mind addressing the conflicts here ?

[Mario-DL]

As this PR in only modifying the docs workflow, I won`t trigger jenkins ci