improve(relayer): Defer deposit version computation (#1847)

getUnfilledDeposits() currently unconditionally computes the deposit
version (i.e. the ConfigStore VERSION value applicable at the deposit
quoteTimestamp), and then filters out all the deposits that have been
filled. Determining the relevant version implies a lot of Array.find()
calls, all of which is wasted when the object is subsequently discarded.

src/utils/FillUtils.ts

@@ -32,11 +32,14 @@ export function getUnfilledDeposits(
 
   return deposits
     .map((deposit) => {
-      const version = hubPoolClient.configStoreClient.getConfigStoreVersionForTimestamp(deposit.quoteTimestamp);
       const { unfilledAmount, invalidFills } = destinationClient.getValidUnfilledAmountForDeposit(deposit);
-      return { deposit, version, unfilledAmount, invalidFills };
+      return { deposit, unfilledAmount, invalidFills };
     })
-    .filter(({ unfilledAmount }) => unfilledAmount.gt(bnZero));
+    .filter(({ unfilledAmount }) => unfilledAmount.gt(bnZero))
+    .map(({ deposit, ...rest }) => {
+      const version = hubPoolClient.configStoreClient.getConfigStoreVersionForTimestamp(deposit.quoteTimestamp);
+      return { deposit, ...rest, version };
+    });
 }
 
 export function getAllUnfilledDeposits(