fix: Restrict keccak256_injective test input to 8 bits (noir-lang#5977)

# Description

## Problem\*

Resolves the keccak256_injective test being flakey

## Summary\*

Makes the keccak256_injective test not flakey.

## Additional Context



## Documentation\*

Check one:
- [X] No documentation needed.
- [ ] Documentation included in this PR.
- [ ] **[For Experimental Features]** Documentation to be submitted in a
separate PR.

# PR Checklist\*

- [X] I have tested the changes locally.
- [X] I have formatted the changes with [Prettier](https://prettier.io/)
and/or `cargo fmt` on default settings.

acvm-repo/acvm/tests/solver.rs

@@ -1584,7 +1584,7 @@ proptest! {
     #[test]
     fn keccak256_injective(inputs_distinct_inputs in any_distinct_inputs(Some(8), 0, 32)) {
         let (inputs, distinct_inputs) = inputs_distinct_inputs;
-        let (result, message) = prop_assert_injective(inputs, distinct_inputs, 32, Some(32), keccak256_op);
+        let (result, message) = prop_assert_injective(inputs, distinct_inputs, 32, Some(8), keccak256_op);
         prop_assert!(result, "{}", message);
     }