chore: remove unused import (#8835)

Please read [contributing guidelines](CONTRIBUTING.md) and remove this
line.

noir-projects/aztec-nr/aztec/src/state_vars/shared_mutable/shared_mutable.nr

@@ -1,7 +1,4 @@
-use dep::protocol_types::{
-    hash::{pedersen_hash, poseidon2_hash}, header::Header, address::AztecAddress,
-    traits::{FromField, ToField}
-};
+use dep::protocol_types::{hash::{pedersen_hash, poseidon2_hash}, address::AztecAddress, traits::{FromField, ToField}};
 
 use crate::context::{PrivateContext, PublicContext, UnconstrainedContext};
 use crate::state_vars::{
@@ -32,10 +29,8 @@ global HASH_SEPARATOR: u32 = 2;
 // can actually use it here
 impl<T, let INITIAL_DELAY: u32, Context> Storage<T> for SharedMutable<T, INITIAL_DELAY, Context> {}
 
-// TODO: extract into a utils module once  we can do arithmetic on generics, i.e. https://github.com/noir-lang/noir/issues/4784
-fn concat_arrays<let N: u32, let M: u32, let O: u32>(arr_n: [Field; N], arr_m: [Field; M]) -> [Field; O] {
-    assert_eq(N + M, O);
-    let mut out: [Field; O] = [0; O];
+fn concat_arrays<let N: u32, let M: u32>(arr_n: [Field; N], arr_m: [Field; M]) -> [Field; N + M] {
+    let mut out: [Field; N + M] = [0; N + M];
     for i in 0..N {
         out[i] = arr_n[i];
     }
@@ -222,8 +217,6 @@ impl<T, let INITIAL_DELAY: u32> SharedMutable<T, INITIAL_DELAY, &mut PrivateCont
         value_change: ScheduledValueChange<T>,
         delay_change: ScheduledDelayChange<INITIAL_DELAY>
     ) -> Field {
-        // TODO(#5491 and https://github.com/noir-lang/noir/issues/4784): update this so that we don't need to rely on
-        // ScheduledValueChange serializing to 3 and ScheduledDelayChange serializing to 1
         let concatenated: [Field; 4] = concat_arrays(value_change.serialize(), delay_change.serialize());
         poseidon2_hash(concatenated)
     }