chore: Avoid creating witness for simple multiplications #7208

Job	Run time
build-nargo	2m 31s
build-acvm-js	1m 24s
build-noirc-abi	2m 9s
build-noir-wasm	3m 56s
ACVM JS (Node.js)	45s
ACVM JS (Browser)	1m 20s
noirc_abi	1m 43s
noir-js-backend-barretenberg	46s
Example scripts	17s
noir_codegen	1m 26s
Noir JS	1m 33s
Integration Tests (Browser)	5m 46s
Integration Tests (Node)	3m 32s
noir_wasm	1m 40s
End	1s
	28m 49s

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