Fix: Use onyxData prefix for optimisticData/successData/failureData in Split.ts

The isLastTransactionInReport block referenced bare optimisticData,
successData, and failureData variables which don't exist in the
updateSplitTransactions scope. Changed to onyxData.optimisticData?,
onyxData.successData?, and onyxData.failureData? to match the
existing pattern in this function.

Co-authored-by: Lydia Barclay <lydiabarclay@users.noreply.github.com>

Author: MelvinBot

src/libs/actions/IOU/Split.ts

@@ -1449,7 +1449,7 @@ function updateSplitTransactions({
         });
         const isLastTransactionInReport = Object.values(allTransactionsList ?? {}).filter((itemTransaction) => itemTransaction?.reportID === expenseReportID).length === 1;
         if (isLastTransactionInReport) {
-            optimisticData.push({
+            onyxData.optimisticData?.push({
                 onyxMethod: Onyx.METHOD.MERGE,
                 key: `${ONYXKEYS.COLLECTION.REPORT}${transactionData.reportID}`,
                 value: {
@@ -1459,12 +1459,12 @@ function updateSplitTransactions({
                     },
                 },
             });
-            successData.push({
+            onyxData.successData?.push({
                 onyxMethod: Onyx.METHOD.SET,
                 key: `${ONYXKEYS.COLLECTION.REPORT}${transactionData.reportID}`,
                 value: null,
             });
-            failureData.push({
+            onyxData.failureData?.push({
                 onyxMethod: Onyx.METHOD.MERGE,
                 key: `${ONYXKEYS.COLLECTION.REPORT}${transactionData.reportID}`,
                 value: {
@@ -1473,7 +1473,7 @@ function updateSplitTransactions({
                 },
             });
             if (expenseReport?.parentReportID && expenseReport?.parentReportActionID) {
-                optimisticData.push({
+                onyxData.optimisticData?.push({
                     onyxMethod: Onyx.METHOD.MERGE,
                     key: `${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${expenseReport?.parentReportID}`,
                     value: {
@@ -1482,7 +1482,7 @@ function updateSplitTransactions({
                         },
                     },
                 });
-                successData.push({
+                onyxData.successData?.push({
                     onyxMethod: Onyx.METHOD.MERGE,
                     key: `${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${expenseReport?.parentReportID}`,
                     value: {
@@ -1491,7 +1491,7 @@ function updateSplitTransactions({
                         },
                     },
                 });
-                failureData.push({
+                onyxData.failureData?.push({
                     onyxMethod: Onyx.METHOD.MERGE,
                     key: `${ONYXKEYS.COLLECTION.REPORT_ACTIONS}${expenseReport?.parentReportID}`,
                     value: {