do not use the average buy price as the first value of the market price chart

apps/api/src/app/portfolio/portfolio.service.ts

@@ -793,10 +793,7 @@ export class PortfolioService {
           historicalDataArray.push({
             date,
             averagePrice: currentAveragePrice,
-            marketPrice:
+            marketPrice,
-              historicalDataArray.length > 0
-                ? marketPrice
-                : currentAveragePrice,
             quantity: currentQuantity
           });