Task/refactor getDividends() from async to sync (#6222)

* Refactor from async to sync

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

@@ -329,7 +329,7 @@ export class PortfolioController {
       types: ['DIVIDEND']
     });
 
-    let dividends = await this.portfolioService.getDividends({
+    let dividends = this.portfolioService.getDividends({
       activities,
       groupBy
     });

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

@@ -325,13 +325,13 @@ export class PortfolioService {
     };
   }
 
-  public async getDividends({
+  public getDividends({
     activities,
     groupBy
   }: {
     activities: Activity[];
     groupBy?: GroupBy;
-  }): Promise<InvestmentItem[]> {
+  }): InvestmentItem[] {
     let dividends = activities.map(({ currency, date, value }) => {
       return {
         date: format(date, DATE_FORMAT),