chore(*): remove tab index from expand/collapse indicator

Author: ddincheva

projects/igniteui-angular/src/lib/grids/grid/expandable-cell.component.html

@@ -31,7 +31,7 @@
 <ng-container *ngIf="showExpanderIndicator">
     <div #indicator
          class="igx-grid__tree-grouping-indicator"
-         (click)="toggle($event)" (focus)="onIndicatorFocus()" tabindex="-1">
+         (click)="toggle($event)" (focus)="onIndicatorFocus()">
          <ng-container *ngTemplateOutlet="iconTemplate; context: { $implicit:  this }">
         </ng-container>
     </div>

projects/igniteui-angular/src/lib/grids/tree-grid/tree-cell.component.html

@@ -36,7 +36,7 @@
          *ngIf="!isLoading"
          class="igx-grid__tree-grouping-indicator"
          [ngStyle]="{'visibility': showIndicator ? 'visible' : 'hidden'}"
-         (click)="toggle($event)" (focus)="onIndicatorFocus()" tabindex="-1">
+         (click)="toggle($event)" (focus)="onIndicatorFocus()">
          <ng-container *ngTemplateOutlet="iconTemplate; context: { $implicit:  this }">
         </ng-container>
         <ng-container *ngTemplateOutlet="pinnedIndicatorTemplate; context: context">