[23857] Branchout 4.3.x

[MiguelCompany]

Description

This makes the master branch be 4.3.x, in preparation for the next minor release 4.3.0

Contributor Checklist

• Commit messages follow the project guidelines.
• 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
• NO: New feature has been documented/Current behavior is correctly described in the documentation.
  • Will be done as part of the Fast DDS branchout to 3.5.x
• N/A: 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.