feat(cli): use rusty_alloc on Linux

[mansiverma897993]

Closes #5505.

Replaces jemallocator with rusty_alloc_api::RustyAlloc for Linux CLI and benchmarks, and removes the obsoleteCloses #5505.

Replaces jemallocator with rusty_alloc_api::RustyAlloc for Linux CLI and benchmarks, and removes the obsolete Nix jemalloc CFLAGS workaround. Windows and macOS allocator selection is unchanged.

Tests: not run locally because rustc and cargo-make are unavailable in this workspace; Cargo manifests and lockfile parse successfully, and git diff --check passes. CI pending. Nix jemalloc CFLAGS workaround. Windows and macOS allocator selection is unchanged.

Tests: not run locally because rustc and cargo-make are unavailable in this workspace; Cargo manifests and lockfile parse successfully, and git diff --check passes. CI pending.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	53,578	53,578	0
Passed	51,432	51,432	0
Ignored	1,648	1,648	0
Failed	498	498	0
Panics	0	0	0
Conformance	95.99%	95.99%	0.00%

Tested main commit: 257bc301afa0cda88f470a8452251ade54d516e3
Tested PR commit: fd7a3fe29ffcce82a6015a4d71bbca5f4bb3ab6f
Compare commits: 257bc30...fd7a3fe

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.89%. Comparing base (6ddc2b4) to head (fd7a3fe).
⚠️ Report is 1052 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5515       +/-   ##
===========================================
+ Coverage   47.24%   62.89%   +15.65%     
===========================================
  Files         476      536       +60     
  Lines       46892    60286    +13394     
===========================================
+ Hits        22154    37918    +15764     
+ Misses      24738    22368     -2370     

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