Remove unused ELF loader test debug helpers

[0xcharry]

Delete unused debug helpers (write_instruction_to_file, write_memory_to_file, debug_elf_file) from vm/src/elf/loader.rs tests, removing dead code and unused imports, keep the existing ELF parsing test unchanged; reduces noise and potential unused warnings

[github-actions]

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[sjudson]

These were deliberately left around as they might be helpful in the near future.