Improves debug build times.

[esdrubal]

Description

Adds DCE before running other optimizations on the backend.

Running DCE before other optimizations reduces compile time in compolabs project from over 40 minutes to 76 seconds.

Fixes #5769

Checklist

• I have linked to any relevant issues.
• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation where relevant (API docs, the reference, and the Sway book).
  • If my change requires substantial documentation changes, I have requested support from the DevRel team
• I have added tests that prove my fix is effective or that my feature works.
• I have added (or requested a maintainer to add) the necessary Breaking* or New Feature labels where relevant.
• I have done my best to ensure that my PR adheres to the Fuel Labs Code Review Standards.
• I have requested a review from the relevant team or maintainers.

[github-actions]

Benchmark for 7438cf4

Click to view benchmark

Test	Base	PR	%
code_action	5.3±0.15ms	5.3±0.09ms	0.00%
code_lens	292.0±4.22ns	294.9±5.50ns	+0.99%
compile	6.1±0.03s	6.0±0.06s	-1.64%
completion	4.8±0.01ms	4.8±0.08ms	0.00%
did_change_with_caching	6.0±0.07s	6.0±0.09s	0.00%
document_symbol	1005.5±40.44µs	957.0±25.39µs	-4.82%
format	75.8±1.06ms	75.2±0.76ms	-0.79%
goto_definition	371.0±10.08µs	364.3±11.92µs	-1.81%
highlight	8.8±0.17ms	8.8±0.17ms	0.00%
hover	602.4±8.25µs	604.0±19.74µs	+0.27%
idents_at_position	128.1±0.21µs	122.1±0.76µs	-4.68%
inlay_hints	667.1±24.10µs	658.0±12.96µs	-1.36%
on_enter	491.9±13.26ns	491.5±11.91ns	-0.08%
parent_decl_at_position	3.6±0.06ms	3.6±0.05ms	0.00%
prepare_rename	367.9±4.76µs	361.0±3.67µs	-1.88%
rename	9.3±0.17ms	9.3±0.20ms	0.00%
semantic_tokens	1076.7±17.55µs	1039.2±14.75µs	-3.48%
token_at_position	365.5±2.09µs	362.0±2.49µs	-0.96%
tokens_at_position	3.6±0.03ms	3.6±0.03ms	0.00%
tokens_for_file	414.1±2.86µs	411.0±1.50µs	-0.75%
traverse	48.8±1.53ms	48.9±1.44ms	+0.20%

[github-actions]

Benchmark for b73d540

Click to view benchmark

Test	Base	PR	%
code_action	5.5±0.21ms	5.5±0.21ms	0.00%
code_lens	290.8±5.31ns	293.8±10.72ns	+1.03%
compile	6.4±0.09s	6.5±0.07s	+1.56%
completion	5.0±0.19ms	5.1±0.37ms	+2.00%
did_change_with_caching	6.4±0.07s	6.4±0.09s	0.00%
document_symbol	1028.2±33.41µs	971.1±19.64µs	-5.55%
format	77.3±1.26ms	75.7±1.42ms	-2.07%
goto_definition	378.5±10.91µs	371.9±5.20µs	-1.74%
highlight	9.0±0.30ms	8.9±0.25ms	-1.11%
hover	616.7±8.55µs	614.3±11.32µs	-0.39%
idents_at_position	122.5±0.61µs	122.7±2.70µs	+0.16%
inlay_hints	666.7±33.62µs	666.3±28.65µs	-0.06%
on_enter	478.1±5.01ns	489.6±24.90ns	+2.41%
parent_decl_at_position	3.7±0.07ms	3.6±0.06ms	-2.70%
prepare_rename	367.7±5.06µs	370.9±5.84µs	+0.87%
rename	9.5±0.23ms	9.6±0.38ms	+1.05%
semantic_tokens	1062.1±114.23µs	1075.6±14.99µs	+1.27%
token_at_position	369.9±4.07µs	366.7±4.31µs	-0.87%
tokens_at_position	3.6±0.08ms	3.7±0.10ms	+2.78%
tokens_for_file	410.0±3.05µs	417.5±7.05µs	+1.83%
traverse	50.9±0.99ms	52.1±1.05ms	+2.36%