TestBed.overrideComponent doesn't work with AOT and webpack

### Command

test

### Is this a regression?

- [ ] Yes, this behavior used to work in the previous version

### The previous version in which this bug was not present was

_No response_

### Description

TestBed.overrideComponent and TestBed.overrideModule don't seem to work with karma, webpack builder (builderMode: browser) and aot enabled. Changing any of these settings, so builderMode: application or disabling aot "fixes" the problem. The same issue was reported here https://github.com/angular/angular-cli/issues/30017 but i guess it was only fixed for esbuild? Is there any workaround for this? or can it be fixed for angular20?

### Minimal Reproduction

Create a simple valid component, turn on AOT for Karma, and make a test where you use TestBed.overrideComponent to reset metadata. You don't even need to specify an actual override in the second parameter to trigger the issue: TestBed.overrideComponent(YourComponent, {}) triggers the failure.

builderMode: browser needs to be set

### Exception or Error

```text
Error: App class doesn't have @Component decorator or is missing metadata.
at invalidTypeError (node_modules/@angular/core/fesm2022/testing.mjs:1661:12)
at forEach (node_modules/@angular/core/fesm2022/testing.mjs:1084:23)
at asyncGeneratorStep (node_modules/@babel/runtime/helpers/esm/asyncToGenerator.js:3:1)
at apply (node_modules/@babel/runtime/helpers/esm/asyncToGenerator.js:17:1)
at _ZoneDelegate.invoke (node_modules/zone.js/fesm2015/zone.js:398:28)
at ProxyZoneSpec.onInvoke (node_modules/zone.js/fesm2015/zone-testing.js:2132:39)
```

### Your Environment

```text
_ _ ____ _ ___
/ \ _ __ __ _ _ _| | __ _ _ __ / ___| | |_ _|
/ △ \ | '_ \ / _` | | | | |/ _` | '__| | | | | | |
/ ___ \| | | | (_| | |_| | | (_| | | | |___| |___ | |
/_/ \_\_| |_|\__, |\__,_|_|\__,_|_| \____|_____|___|
|___/

Angular CLI: 20.3.18
Node: 22.22.0
Package Manager: npm 10.9.4
OS: win32 x64

Angular: 20.3.17
... common, compiler, compiler-cli, core, forms
... platform-browser, router

Package Version
---------------------------------------
@angular-devkit/architect 0.2003.18
@angular-devkit/build-angular 20.3.16
@angular-devkit/core 20.3.18
@angular-devkit/schematics 20.3.18
@angular/build 20.3.18
@angular/cli 20.3.18
@schematics/angular 20.3.18
rxjs 7.8.2
typescript 5.9.3
zone.js 0.15.1
```

### Anything else relevant?

_No response_

Bắt đầu với bản tái hiện tối thiểu: một bài kiểm thử component sử dụng TestBed.overrideComponent hoặc TestBed.overrideModule với Karma, webpack builder ở browser mode và bật AOT. So sánh lỗi với application builder mode hoặc khi tắt AOT, sau đó xác minh rằng bài kiểm thử override chạy mà không gặp lỗi thiếu metadata @Component trong cấu hình bị ảnh hưởng.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.