[20965] Fix Python Installation version in Github CI. Address failing system tests environment issues. (backport #4759)

[mergify]

Description

This PR addresses failing github CI system tests.

• It fixes Python installation version in Windows & Ubuntu Github CIs (macOs was already doing it).
• Selects the appropriate python version in the launcher used in .bat tool files by means of an environment variable PYTHON_VERSION {Major.Minor}.
• Prevents Qt from setting-up Python, as we are who manage the Python installation

Notes:

• In windows, pywin32 is not listed as a required python package at the Python Dependencies step as it is a requirement of colcon and it is installed along with it.
• Python version is not fixed in the sanitizers jobs since system tests are not run there.

Work done in #4731 precedes this PR.

@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 Any new configuration API has an equivalent XML API (with the corresponding XSD extension)

• 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 #4759 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 3b2e781 has failed:

On branch mergify/bp/2.6.x/pr-4759
Your branch is up to date with 'origin/2.6.x'.

You are currently cherry-picking commit 3b2e781f3.
  (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:   .github/workflows/reusable-ubuntu-ci.yml
	modified:   .github/workflows/reusable-windows-ci.yml
	modified:   tools/fastdds/fastdds.bat
	modified:   tools/fastdds/ros-discovery.bat

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   test/system/tools/fastdds/CMakeLists.txt

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]

Added cherry-pick from #4447

[Mario-DL]

@richiprosima please test this

[Mario-DL]

@richiprosima please test windows

[Mario-DL]

This last CI was launched in windows as the latest cherry-pick only affects .bat files. The entire ci was launched for fe4f2cf where the failed tests were unrelated to this PR.