chore: remove a few object clones

[reubeno]

No description provided.

[github-actions]

Test Results

    2 files      9 suites   1m 51s ⏱️
  666 tests   666 ✅ 0 💤 0 ❌
1 318 runs  1 318 ✅ 0 💤 0 ❌

Results for commit 5a0b77a.

[github-actions]

Performance Benchmark Report

Benchmark name	Baseline (μs)	Test/PR (μs)	Delta (μs)	Delta %
clone_shell_object	17.86 μs	18.06 μs	0.20 μs	🟠 +1.12%
eval_arithmetic	0.17 μs	0.17 μs	-0.00 μs	⚪ Unchanged
expand_one_string	1.62 μs	1.58 μs	-0.04 μs	⚪ Unchanged
for_loop	22.26 μs	21.91 μs	-0.35 μs	🟢 -1.59%
function_call	2.45 μs	2.31 μs	-0.14 μs	⚪ Unchanged
instantiate_shell	57.24 μs	56.96 μs	-0.29 μs	⚪ Unchanged
instantiate_shell_with_init_scripts	21832.60 μs	21626.83 μs	-205.77 μs	⚪ Unchanged
parse_bash_completion	1642.46 μs	1672.87 μs	30.41 μs	🟠 +1.85%
parse_sample_script	1.74 μs	1.78 μs	0.05 μs	🟠 +2.88%
run_echo_builtin_command	15.06 μs	15.29 μs	0.22 μs	⚪ Unchanged
run_one_external_command	2297.74 μs	2005.66 μs	-292.09 μs	🟢 -12.71%
tokenize_sample_script	2.87 μs	2.83 μs	-0.04 μs	🟢 -1.50%

Code Coverage Report: Only Changed Files listed

Package	Base Coverage	New Coverage	Difference
brush-core/src/interp.rs	🟢 91.46%	🟢 91.48%	🟢 0.02%
Overall Coverage	🟢 77.81%	🟢 77.82%	🟢 0.01%

Minimum allowed coverage is 70%, this run produced 77.82%