DEV: Fix an error in topic deletion (#20440)

Spotted as log entry in tests:

```
TypeError: Cannot read properties of undefined (reading 'force_destroy')
```

app/assets/javascripts/discourse/app/controllers/delete-topic-confirm.js

@@ -1,4 +1,4 @@
-import Controller, { inject as controller } from "@ember/controller";
+import Controller from "@ember/controller";
 import I18n from "I18n";
 import ModalFunctionality from "discourse/mixins/modal-functionality";
 import { action } from "@ember/object";
@@ -7,7 +7,6 @@ import discourseComputed from "discourse-common/utils/decorators";
 // Modal that displays confirmation text when user deletes a topic
 // The modal will display only if the topic exceeds a certain amount of views
 export default Controller.extend(ModalFunctionality, {
-  topicController: controller("topic"),
   deletingTopic: false,
 
   @discourseComputed("deletingTopic")
@@ -25,7 +24,7 @@ export default Controller.extend(ModalFunctionality, {
   deleteTopic() {
     this.set("deletingTopic", true);
 
-    this.topicController.model
+    this.model
       .destroy(this.currentUser)
       .then(() => this.send("closeModal"))
       .catch(() => {

app/assets/javascripts/discourse/app/models/topic.js

@@ -453,7 +453,7 @@ const Topic = RestModel.extend({
   },
 
   // Delete this topic
-  destroy(deleted_by, opts) {
+  destroy(deleted_by, opts = {}) {
     return ajax(`/t/${this.id}`, {
       data: { context: window.location.pathname, ...opts },
       type: "DELETE",