perf: Remove unnecessary allocations in syscall handlers #1768

Job	Run time
tests-sdk (nexus-sdk)	4m 9s
wasm-tests (nexus-vm-prover)	17m 36s
fmt	14s
wasm-tests (nexus-vm)	1m 10s
check-and-clippy	2m 29s
tests (nexus-vm)	1m 37s
tests (nexus-vm-prover)	4m 38s
tests (nexus-common)	44s
tests (testing-framework)	8m 4s
tests (nexus-vm-prover2)	6m 45s
tests (nexus-precompiles)	1m 23s
run-sdk-examples (fact)	39s
run-sdk-examples (multiply)	44s
run-sdk-examples (galeshapley)	44s
run-sdk-examples (palindromes)	37s
run-sdk-examples (lambda_calculus)	41s
run-sdk-examples (keccak)	50s
run-sdk-examples (fib)	41s
run-sdk-examples (simple_hash)	43s
	54m 28s

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