CHORE: Remove Quarto installation from CI workflows and enable cheatsheet option in documentation build

[eblanco-ansys]

This pull request updates the documentation build process in the CI workflows to improve how the Quarto dependency is managed and to make the cheatsheet feature configurable. The main changes involve removing explicit Quarto installation steps and instead relying on the needs-quarto flag in the documentation build action. This was introduced in #7331, but it's not needed anymore. Additionally, an environment variable is introduced to optionally include the cheatsheet in the documentation.

Documentation build process improvements:

• Removed manual Quarto installation steps from .github/workflows/ci-release.yml, .github/workflows/ci_cd.yml, and .github/workflows/nightly-docs.yml, streamlining the workflow and reducing redundancy. [1] [2] [3]
• Set the needs-quarto input to true in the documentation build steps of the affected workflows, ensuring Quarto is installed only when required by the action. [1] [2]

Cheatsheet configurability:

• Added the PYAEDT_DOC_BUILD_CHEATSHEET environment variable to .github/workflows/ci_cd.yml, allowing the cheatsheet to be included or excluded from the documentation build based on this setting.
• Updated doc/source/conf.py to conditionally add the cheatsheet to html_theme_options only if PYAEDT_DOC_BUILD_CHEATSHEET is not set to "False".## Description
  Please provide a brief description of the changes made in this pull request.

Checklist

• I have tested my changes locally.
• I have added necessary documentation or updated existing documentation.
• I have followed the coding style guidelines of this project.
• I have added appropriate tests (unit, integration, system).
• I have reviewed my changes before submitting this pull request.
• I have linked the issue or issues that are solved by the PR if any.
• I have agreed with the Contributor License Agreement (CLA).

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