shielded-pool: remove update_token_supply

In #3640, we added two helper methods:
- `increase_token_supply`
- `decrease_token_supply`

These methods are somewhat similar, and objectively are more
verbose than a single `update_token_supply` method. However,
it seems an improvement to not have to do any cognitive work
to piece together whether a method call increases or decreases
the token supply.

Another advantage of this approach is that one can easily use
rust-analyzer to filter for places that increase the token supply
vs. places where it is being shrinked.

crates/core/component/shielded-pool/src/component/note_manager.rs

@@ -57,7 +57,7 @@ pub trait NoteManager: StateWrite {
 
         let note = Note::from_parts(*address, value, Rseed(rseed_bytes))?;
         // Now record the note and update the total supply:
-        self.update_token_supply(&value.asset_id, value.amount.value() as i128)
+        self.increase_token_supply(&value.asset_id, value.amount)
             .await?;
         self.add_note_payload(note.payload(), source).await;
 

crates/core/component/shielded-pool/src/component/supply.rs

@@ -92,46 +92,6 @@ pub trait SupplyWrite: StateWrite {
         self.put(key, new_supply);
         Ok(())
     }
-
-    // TODO: should this really be separate from note management?
-    // #[instrument(skip(self, change))]
-    async fn update_token_supply(&mut self, asset_id: &asset::Id, change: i128) -> Result<()> {
-        let key = state_key::token_supply(asset_id);
-        let current_supply: Amount = self.get(&key).await?.unwrap_or(0u64.into());
-
-        // TODO: replace with a single checked_add_signed call when mixed_integer_ops lands in stable (1.66)
-        let new_supply: Amount = if change < 0 {
-            current_supply
-                .value()
-                .checked_sub(change.unsigned_abs())
-                .ok_or_else(|| {
-                    anyhow::anyhow!(
-                        "underflow updating token {} supply {} with delta {}",
-                        asset_id,
-                        current_supply,
-                        change
-                    )
-                })?
-                .into()
-        } else {
-            current_supply
-                .value()
-                .checked_add(change as u128)
-                .ok_or_else(|| {
-                    anyhow::anyhow!(
-                        "overflow updating token {} supply {} with delta {}",
-                        asset_id,
-                        current_supply,
-                        change
-                    )
-                })?
-                .into()
-        };
-        tracing::debug!(?current_supply, ?new_supply, ?change);
-
-        self.put(key, new_supply);
-        Ok(())
-    }
 }
 
 impl<T: StateWrite + ?Sized> SupplyWrite for T {}

crates/core/component/shielded-pool/src/component/transfer.rs

@@ -136,7 +136,7 @@ pub trait Ics20TransferWriteExt: StateWrite {
             );
 
             // update supply tracking of burned note
-            self.update_token_supply(&withdrawal.denom.id(), -(withdrawal.amount.value() as i128))
+            self.decrease_token_supply(&withdrawal.denom.id(), withdrawal.amount)
                 .await
                 .expect("couldn't update token supply in ics20 withdrawal!");
         }