test(language-service): delete expression-cases.ts (#36468)

This commit deletes `expression-cases.ts` and moves the test cases to
inline expressions in TEST_TEMPLATE.

PR Close #36468

packages/language-service/test/project/app/parsing-cases.ts

@@ -169,6 +169,7 @@ export class TemplateReference {
   birthday = new Date();
   readonlyHeroes: ReadonlyArray<Readonly<Hero>> = this.heroes;
   constNames = [{name: 'name'}] as const;
+  private myField = 'My Field';
 }
 
 @Component({