chore: address TODO in compat.nr (noir-lang#5339)

# Description

## Problem\*

Resolves <!-- Link to GitHub Issue -->

## Summary\*

This PR addresses a TODO in the stdlib now that noir-lang#5245 is resolved.

## 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.

noir_stdlib/src/compat.nr

@@ -1,18 +1,7 @@
-global BN254_MODULUS_BE_BYTES: [u8; 32] = [
+global BN254_MODULUS_BE_BYTES: [u8] = &[
     48, 100, 78, 114, 225, 49, 160, 41, 184, 80, 69, 182, 129, 129, 88, 93, 40, 51, 232, 72, 121, 185, 112, 145, 67, 225, 245, 147, 240, 0, 0, 1
 ];
 
 pub fn is_bn254() -> bool {
-    // TODO: refactor this once https://github.com/noir-lang/noir/issues/5245 is resolved.
-    let modulus_bytes = crate::field::modulus_be_bytes();
-    if modulus_bytes.len() == 32 {
-        let mut modulus_bytes_array: [u8; 32] = [0; 32];
-        for i in 0..32 {
-            modulus_bytes_array[i] = modulus_bytes[i];
-        }
-
-        modulus_bytes_array == BN254_MODULUS_BE_BYTES
-    } else {
-        false
-    }
+    crate::field::modulus_be_bytes() == BN254_MODULUS_BE_BYTES
 }