CI: Remove support for Ubuntu 24.04

[RytoEX]

Description

Remove Ubuntu 24.04 builds and move all Ubuntu 24.04 CI jobs to Ubuntu 26.04.

Motivation and Context

Per:

• Dropping Support for Ubuntu 24.04, Qt 6.4, and FFmpeg 6.1 #13570

How Has This Been Tested?

It hasn't.

Types of changes

• CI

Checklist:

• I have read the contributing document.
• My code has been run through clang-format.
• My code follows the project's style guidelines
• My code is not on the master branch.
• My code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.