[24518] Fix null-dereference build (backport #6393)

[mergify]

Description

This PR fixes Ubuntu alternative build workflow, which was failing since the 12th of May: https://github.com/eProsima/Fast-DDS/actions/runs/25701062043/job/75462671897

@Mergifyio backport 3.4.x 3.2.x 2.14.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: Any new configuration API has an equivalent XML API (with the corresponding XSD extension)

• Changes are backport compatible: they do NOT break ABI nor change library core behavior.

• 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.
• If this is a critical bug fix, backports to the critical-only supported branches have been requested.
• Check CI results: changes do not issue any warning.
• Check CI results: failing tests are unrelated with the changes.

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This is an automatic backport of pull request #6393 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of f2790b8 has failed:

On branch mergify/bp/2.14.x/pr-6393
Your branch is up to date with 'origin/2.14.x'.

You are currently cherry-picking commit f2790b8d5.
  (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/rm <file>..." as appropriate to mark resolution)
	deleted by us:   src/cpp/fastdds/xtypes/dynamic_types/DynamicTypeImpl.hpp
	deleted by us:   src/cpp/fastdds/xtypes/dynamic_types/DynamicTypeMemberImpl.hpp

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