[Misc] Use dracut on CentOS and skip clone if repo exists for EP kernel installation

[minosfuture]

Purpose

• Use dracut for init ramdisk creation on CentOS. (update-initramfs is for Debian)
• Skip git clone EP kernel repos

Test Plan

run scripts locally

Test Result

scripts work well

(Optional) Documentation Update

[github-actions]

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[gemini-code-assist]

Code Review

This pull request improves system configuration and installation scripts by using dracut on CentOS and skipping cloning if repos exist. The review focuses on improving the robustness of the repository cloning logic to handle cases of partial or failed clones, which could otherwise cause script failures on subsequent runs. Changes were suggested to ensure the scripts are more resilient.