Mono repo release skipped when only the root project is updated

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Please provide the following details.

#### Environment details

- OS: ubuntu
- Node.js version: v22.19.0
- npm version: 10.9.3
- `release-please` version: v17.1.2

#### Steps to reproduce

I have a monorepo setup, `release-please-config.json`
```
"packages": {
"packages/bla": {},
".": {
"include-component-in-tag": false,
}
},
```

When I change package `bla`, release-please correctly tags bla and the root library. However, if I only change the root library it doesn't.

Having a look at the code, I can see `buildRelease` is skipped here: https://github.com/googleapis/release-please/blob/2ec56e7c9b3fd36b2c7cabfbad9eb949197224ba/src/strategies/base.ts#L648

Adding a check like `&& component !== ''` seems to work for me https://github.com/googleapis/release-please/blob/2ec56e7c9b3fd36b2c7cabfbad9eb949197224ba/src/strategies/base.ts#L645

However, it breaks this test which I don't understand. https://github.com/googleapis/release-please/blob/2ec56e7c9b3fd36b2c7cabfbad9eb949197224ba/test/manifest.ts#L5604

Making sure to follow these steps will guarantee the quickest resolution possible.

Thanks!