chore: fix deletion target lint failure (#12572)

src/lib/dialog/dialog-ref.ts

@@ -190,7 +190,7 @@ export class MatDialogRef<T, R = any> {
   /**
    * Gets an observable that is notified when the dialog is finished opening.
    * @deprecated Use `afterOpened` instead.
-   * @deletion-target 8.0.0
+   * @breaking-change 8.0.0
    */
   afterOpen(): Observable<void> {
     return this.afterOpened();
@@ -199,7 +199,7 @@ export class MatDialogRef<T, R = any> {
   /**
    * Gets an observable that is notified when the dialog has started closing.
    * @deprecated Use `beforeClosed` instead.
-   * @deletion-target 8.0.0
+   * @breaking-change 8.0.0
    */
   beforeClose(): Observable<R | undefined> {
     return this.beforeClosed();

src/lib/dialog/dialog.ts

@@ -85,7 +85,7 @@ export class MatDialog {
   /**
    * Stream that emits when a dialog has been opened.
    * @deprecated Use `afterOpened` instead.
-   * @deletion-target 8.0.0
+   * @breaking-change 8.0.0
    */
   get afterOpen(): Subject<MatDialogRef<any>> {
     return this.afterOpened;