Feature/eliminate OnDestroy lifecycle hook from markets page component

Remove unused OnDestroy lifecycle hook and Subject from the markets
page component. The unsubscribeSubject was created but never piped
into any subscriptions, making the entire cleanup pattern dead code.

Follows the same DestroyRef migration direction as #6419, though this
component has no subscriptions that need the replacement pattern.

Fixes #6652

apps/client/src/app/pages/markets/markets-page.component.ts

@@ -1,7 +1,6 @@
 import { GfHomeMarketComponent } from '@ghostfolio/client/components/home-market/home-market.component';
 
-import { Component, OnDestroy } from '@angular/core';
-import { Subject } from 'rxjs';
+import { Component } from '@angular/core';
 
 @Component({
   host: { class: 'page' },
@@ -10,11 +9,4 @@ import { Subject } from 'rxjs';
   styleUrls: ['./markets-page.scss'],
   templateUrl: './markets-page.html'
 })
-export class GfMarketsPageComponent implements OnDestroy {
-  private unsubscribeSubject = new Subject<void>();
-
-  public ngOnDestroy() {
-    this.unsubscribeSubject.next();
-    this.unsubscribeSubject.complete();
-  }
-}
+export class GfMarketsPageComponent {}