feat(minifier): remove unused variable declaration

[Boshen]

closes #10033

[graphite-app]

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[codspeed-hq]

CodSpeed Instrumentation Performance Report

Merging #11796 will degrade performances by 37.9%

_{Comparing 06-18-feat_minifier_remove_unused_variable_declaration (ea67ff4) with main (b172cef)}

Summary

❌ 4 regressions
✅ 30 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	minifier[RadixUIAdoptionSection.jsx]	66.1 µs	82.2 µs	-19.64%
❌	minifier[binder.ts]	3.5 ms	4.8 ms	-27.62%
❌	minifier[cal.com.tsx]	23.8 ms	38.4 ms	-37.9%
❌	minifier[react.development.js]	1.8 ms	2.8 ms	-34.56%

[Boshen]

I'll resolve the performance regression when I finalize the algorithm.