Reduced heap allocation in LuaJIT analysis plugin

[Arya-1-HR]

Your checklist for this pull request

• I've read the guidelines for contributing to this repository.
• I made sure to follow the project's coding style.
• I've documented every RZ_API function and struct this PR changes.
• I've added tests that prove my changes are effective (required for changes to RZ_API).
• I've updated the Rizin book with the relevant information (if needed).
• I've used AI tools to generate fully or partially these code changes and I'm sure the changes are not copyrighted by somebody else.

Detailed description

Removed heap allocations and used rz_asm_op_setf_asm() API instead.

Test plan

Existing LuaJIT analysis test passes

Closing issues

Partially addressed #4127

[codecov]

Codecov Report

❌ Patch coverage is 71.42857% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.95%. Comparing base (9836b05) to head (1abd8d6).

Files with missing lines	Patch %	Lines
librz/arch/isa/luac/luajit/asm_2.1.c	63.63%	4 Missing ⚠️
librz/arch/isa/luac/luajit/arch_2.1.c	80.00%	2 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
librz/arch/isa/luac/luajit/arch_2.1.c	86.66% <80.00%> (ø)
librz/arch/isa/luac/luajit/asm_2.1.c	69.04% <63.63%> (-3.68%)	⬇️

... and 17 files with indirect coverage changes

---

Continue to review full report in Codecov by Harness.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9836b05...1abd8d6. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.