test(compiler): fix unwanted `!` operators (#36741)

The `I18nComponent` was using `!` for some of its properties
because it had not initialized them. This is now resolved by explictly
marking them as optional.

PR Close #36741

packages/compiler/test/i18n/integration_common.ts

@@ -19,12 +19,9 @@ import {expect} from '@angular/platform-browser/testing/src/matchers';
   template: '',
 })
 export class I18nComponent {
-  // TODO(issue/24571): remove '!'.
-  count!: number;
-  // TODO(issue/24571): remove '!'.
-  sex!: string;
-  // TODO(issue/24571): remove '!'.
-  sexB!: string;
+  count?: number;
+  sex?: string;
+  sexB?: string;
   response: any = {getItemsList: (): any[] => []};
 }