[Ubuntu] Add support for Ubuntu 26.04 (LTS)

[siramvikram]

This issue is created to track progress for the work to enable Ubuntu 26.04 support for .NET 8.0 , 9.0 and 10

• [All Product Teams] Compatibility check and infra update
• Do a compatibility check for the product with the new OS
• Replace docker tags used in builds across repos and branches
• Update CI legs to latest updated Dockerfile
• Ensure that the correct Docker images used by teams are built in the dotnet-buildtools-prereqs (if applicable)

Resources:
https://releases.ubuntu.com/