Disksize update

[moisesjgomez]

Overview/Summary

This PR fixes/adds/changes/removes

1. Adds option to customize OS disk size larger than image size

Testing Evidence

Deployments using custom size and without custom size deployed successfully.

As part of this Pull Request I have

• [ ] Read the Contribution Guide and ensured this PR is compliant with the guide
• [ ] Ensured the resource API versions in .bicep file/s I am adding/editing are using the latest API version possible
• [ ] Checked for duplicate Pull Requests
• [ ] Associated it with relevant GitHub Issues
• [ ] (AVD LZA Team Only) Associated it with relevant ADO Items
• [ ] Ensured my code/branch is up-to-date with the latest changes in the main branch
• [ ] Performed testing and provided evidence.
• [ ] Updated relevant and associated documentation (e.g. Contribution Guide, Module READMEs, Docs etc.)