[DURACOM-224] fix infinite scroll

(cherry picked from commit 2afa473cfb)

src/app/shared/dso-selector/dso-selector/dso-selector.component.html

@@ -7,12 +7,12 @@
            [formControl]="input" ngbAutofocus (keyup.enter)="selectSingleResult()">
 </div>
 <div class="dropdown-divider"></div>
-<div class="scrollable-menu list-group">
+<div id="scrollable-menu-dso-selector-{{randomSeed}}" class="scrollable-menu list-group">
   <div
     infiniteScroll
     [infiniteScrollDistance]="1"
     [infiniteScrollThrottle]="0"
-    [infiniteScrollContainer]="'.scrollable-menu'"
+    [infiniteScrollContainer]="'#scrollable-menu-dso-selector-' + randomSeed"
     [fromRoot]="true"
     (scrolled)="onScrollDown()">
     <ng-container *ngIf="listEntries$ | async">

src/app/shared/dso-selector/dso-selector/dso-selector.component.ts

@@ -141,6 +141,11 @@ export class DSOSelectorComponent implements OnInit, OnDestroy {
    */
   public subs: Subscription[] = [];
 
+  /**
+   * Random seed of 4 characters to avoid duplicate ids
+   */
+  randomSeed: string = Math.random().toString(36).substring(2, 6);
+
   constructor(
     protected searchService: SearchService,
     protected notifcationsService: NotificationsService,