[ADF-3926] Start Task Cloud: Single selection mode: the default assignee is not part of the list o… (#4175)

* Single selection mode: the default assignee is not part of the list once is removed

* Changing providerDropdown locator

lib/process-services-cloud/src/lib/task/start-task/components/people-cloud/people-cloud.component.ts

@@ -177,6 +177,7 @@ export class PeopleCloudComponent implements OnInit {
     private loadPreSelectUsers() {
         if (!this.isMultipleMode()) {
             this.searchUserCtrl.setValue(this.preSelectUsers[0]);
+            this.preSelectUsers = [];
         }
     }