[23515] Update 3.3.x to be a supported branch

[emiliocuestaf]

Description

This PR updates 3.3.x sources to be considered a supported branch:

• Fix versions in fastdds.repos to the 3.3.x corresponding versions
• Remove mirror, nightly and weekly workflows
• Update master references to 3.3.x
• Update README references to nightly workflows

This PR depends on and must be merged after:

• [23515] Branch out 3.4.x #5940

Contributor Checklist

• Commit messages follow the project guidelines.
• [N/A] 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 backport compatible: they do NOT break ABI nor change library core behavior.
• [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.
• [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.
• 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.

[Mario-DL]

Apart from the comments below, please change the target branch to be 3.3.x instead of master

[Mario-DL]

Also, please, update the description the 3.1.x references to 3.3.x

[Mario-DL]

LGTM with green CI