test: remove unnecessary mut from noir test envs

[alice-aztec]

Summary

• Remove unnecessary mut from Noir test env declarations where the environment is only read/used immutably.
• Keep remaining let mut env declarations that still mutate env via account creation, deploys, or &mut env helper calls.

Test Plan

• git diff --check
• yarn test:nr reached Compilation complete! with Aztec 4.3.0; the outer Hermes command timed out after 600s before the full test command returned.

[github-actions]

Benchmark Comparison

CPU	Cores	RAM	Arch
AMD EPYC 7763 64-Core Processor	16	63 GiB	x64

Contract: escrow

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	(partial) withdraw	532,162	532,162		1,312	1,312		495,400	495,400		6,933	7,107	+174 (+2.5%)
⚪	withdraw	532,162	532,162		736	736		483,700	483,700		6,966	7,120	+154 (+2.2%)
⚪	withdraw_nft	503,323	503,323		736	736		483,700	483,700		6,814	7,186	+372 (+5.5%)

Contract: logic

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	get_escrow	488,339	488,339		128	128		456,000	456,000		6,666	6,822	+156 (+2.3%)
⚪	secret_key_to_public_keys	483,417	483,417		128	128		456,000	456,000		6,622	6,823	+201 (+3.0%)
⚪	share_escrow	387,745	387,745		704	704		474,500	474,500		5,839	5,993	+154 (+2.6%)

Contract: nft

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	burn_private	422,217	422,217		416	416		661,169	661,169		6,128	6,907	+779 (+12.7%)
⚪	burn_public	308,698	308,698		448	448		670,145	670,145		5,239	5,316	+77 (+1.5%)
⚪	mint_to_private	439,895	439,895		960	960		652,042	652,042		6,242	6,363	+121 (+1.9%)
⚪	mint_to_public	308,698	308,698		448	448		670,790	670,790		5,205	5,273	+68 (+1.3%)
⚪	transfer_private_to_private	394,899	394,899		736	736		483,700	483,700		5,898	6,010	+112 (+1.9%)
⚪	transfer_private_to_public	422,293	422,293		416	416		659,249	659,249		6,100	6,237	+137 (+2.2%)
⚪	transfer_public_to_private	436,536	436,536		960	960		652,459	652,459		6,201	6,403	+202 (+3.3%)
⚪	transfer_public_to_public	308,698	308,698		384	384		633,270	633,270		5,202	5,323	+121 (+2.3%)

Contract: token

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	burn_private	447,046	447,046		992	992		682,815	682,815		6,293	6,548	+255 (+4.1%)
⚪	burn_public	308,698	308,698		448	448		668,939	668,939		5,193	5,476	+283 (+5.4%)
⚪	initialize_transfer_commitment	371,233	371,233		704	704		474,500	474,500		5,741	5,941	+200 (+3.5%)
⚪	mint_to_private	440,787	440,787		960	960		651,853	651,853		6,252	6,637	+385 (+6.2%)
⚪	mint_to_public	308,698	308,698		448	448		671,882	671,882		5,177	5,505	+328 (+6.3%)
⚪	transfer_private_to_commitment	404,209	404,209		896	896		495,400	495,400		5,984	6,235	+251 (+4.2%)
⚪	transfer_private_to_private	423,732	423,732		1,312	1,312		495,400	495,400		6,081	6,415	+334 (+5.5%)
⚪	transfer_private_to_public	447,122	447,122		992	992		683,040	683,040		6,285	6,483	+198 (+3.2%)
⚪	transfer_private_to_public_with_commitment	450,566	450,566		1,568	1,568		716,340	716,340		6,310	6,552	+242 (+3.8%)
⚪	transfer_public_to_commitment	308,698	308,698		576	576		658,995	658,995		5,204	5,369	+165 (+3.2%)
⚪	transfer_public_to_private	437,430	437,430		960	960		652,321	652,321		6,240	6,480	+240 (+3.8%)
⚪	transfer_public_to_public	308,698	308,698		448	448		669,014	669,014		5,211	5,361	+150 (+2.9%)

Contract: vault

🚦	Function	Gates			DA Gas			L2 Gas			Proving Time (ms)
		Base	PR	Diff	Base	PR	Diff	Base	PR	Diff	Base	PR	Diff
⚪	deposit_private_to_private	856,726	856,726		1,280	1,280		846,413	846,413		9,712	10,240	+528 (+5.4%)
⚪	deposit_private_to_private_exact	965,570	965,570		1,856	1,856		883,247	883,247		10,614	11,128	+514 (+4.8%)
⚪	deposit_private_to_public	674,318	674,318		768	768		861,235	861,235		8,220	8,624	+404 (+4.9%)
⚪	deposit_public_to_private	554,293	554,293		1,344	1,344		885,660	885,660		7,222	7,639	+417 (+5.8%)
⚪	deposit_public_to_private_exact	709,509	709,509		1,920	1,920		922,656	922,656		8,529	8,985	+456 (+5.3%)
⚪	deposit_public_to_public	308,698	308,698		832	832		901,550	901,550		5,254	5,531	+277 (+5.3%)
⚪	issue_private_to_private_exact	965,570	965,570		1,856	1,856		883,904	883,904		10,593	10,971	+378 (+3.6%)
⚪	issue_private_to_public_exact	783,172	783,172		1,344	1,344		898,951	898,951		9,120	9,372	+252 (+2.8%)
⚪	issue_public_to_private	604,635	604,635		1,344	1,344		894,854	894,854		7,630	8,060	+430 (+5.6%)
⚪	issue_public_to_public	308,698	308,698		832	832		902,237	902,237		5,204	5,427	+223 (+4.3%)
⚪	redeem_private_to_private_exact	962,210	962,210		1,856	1,856		883,751	883,751		10,622	10,726	+104 (+1.0%)
⚪	redeem_private_to_public	674,241	674,241		768	768		858,328	858,328		8,152	8,327	+175 (+2.1%)
⚪	redeem_public_to_private_exact	659,929	659,929		1,920	1,920		922,980	922,980		8,029	8,327	+298 (+3.7%)
⚪	redeem_public_to_public	308,698	308,698		832	832		898,727	898,727		5,170	5,387	+217 (+4.2%)
⚪	withdraw_private_to_private	853,366	853,366		1,280	1,280		846,623	846,623		9,625	10,263	+638 (+6.6%)
⚪	withdraw_private_to_private_exact	962,210	962,210		1,856	1,856		883,700	883,700		10,600	10,829	+229 (+2.2%)
⚪	withdraw_private_to_public_exact	783,094	783,094		1,344	1,344		895,837	895,837		9,131	9,599	+468 (+5.1%)
⚪	withdraw_public_to_private	551,001	551,001		1,344	1,344		885,480	885,480		7,159	7,336	+177 (+2.5%)
⚪	withdraw_public_to_public	308,698	308,698		832	832		899,030	899,030		5,228	5,369	+141 (+2.7%)