OZG-4527 Use CSS dark mode detection (2)

alfa-client/libs/vorgang-detail/src/lib/aktenzeichen-edit-dialog/aktenzeichen-edit-dialog.component.html

@@ -2,7 +2,7 @@
 <form class="form" [formGroup]="formService.form" (ngSubmit)="onSubmit()">
 	<mat-dialog-content>
 		<div class="content">
-			<mat-icon svgIcon="az" class="az_icon" [class.az_icon--active]="hasAktenzeichen$ | async" [class.az_icon--active--dark-mode]="darkMode$ | async"></mat-icon>
+			<mat-icon svgIcon="az" class="az_icon" [class.az_icon--active]="hasAktenzeichen$ | async"></mat-icon>
 			<ozgcloud-text-editor
 				class="az_text"
 				data-test-id="aktenzeichen-edit-dialog-text-editor"