Unit test: Add reporter watermark configuration to angular.json

### Command

test

### Description

After taking advantage of all the new Vitest unit test features in 21.0.0, there is only one configuration item left in the vitest-base.config.ts:

```
export default defineConfig({
test: {
slowTestThreshold: 1000
}
});
```

This is required since the Vitest's [slowTestThreshold](https://vitest.dev/guide/cli.html#slowtestthreshold) default of 300 ms is not adequate for extended test cases.

Ideally this configuration should be available through the angular.json configuration unit-test options, since it would allow the complete removal of the vitest-base.config.ts file.

Maybe follow the nomenclature that you introduced with "coverageWatermarks" and call it "reporterWatermark".

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

先從 angular.json 中的單元測試選項和 vitest-base.config.ts 開始，然後執行儲存庫的單元測試命令，以追蹤選項如何傳遞到 Vitest。確認所需的慢速測試閾值設定可透過 angular.json 接受，並且可以移除 vitest-base.config.ts 而不會遺失設定。

由索引模型根據 Issue 內容生成。