Update ah-ubuntu_22_04-c8g_8x CI runner image — missing common developer tools and outdated versions

Description: The ah-ubuntu_22_04-c8g_8x Graviton4 CI runner image lacks several standard build tools that are preinstalled on GitHub-hosted runners. This causes extra unnecessary setup steps in our llama.cpp CI workflow.

Current issues: • CMake is either missing or too old (< 4.0). • Versions prior to 4.0 contain a known bug in the download logic that breaks KleidiAI src retrieval. • Git LFS is not installed or initialized, which leads to model download failures in tests. • GCC is still version 11.x, missing optimizations and features present in newer versions.

Requested actions:

1. Add CMake ≥ 4.0 (preferably from the Kitware repository).
2. Install and initialize Git LFS globally.
3. Upgrade GCC to a more recent stable version.
4. Install other missing standard tools such as python3-venv
5. Align the Graviton4 runner image with GitHub-hosted runner baselines, which already include these tools by default.

Impact: Missing and outdated tools slow down builds, require redundant dependency setup in CI workflows, and create inconsistencies between Graviton4 and other runners.

Note: This runner is used in upstream llama.cpp CI setup