removing the api name from `config.yaml` is not reflected when generating the package

Even when I update the `config.yaml`, by removing some apis, it will still generate all the libraries corresponding to json files in discovery

```
# Manually curated lists of which APIs should go into which packages, and which
# should be ignored.
packages:
- googleapis:
version: 14.0.0
repository: https://github.com/google/googleapis.dart/tree/master/generated/googleapis
readme: resources/README.md
license: resources/LICENSE
changelog: resources/googleapis/CHANGELOG.md
example: resources/googleapis/examples/main.dart
mono_pkg: resources/googleapis/_mono_pkg.yaml
resolution: workspace
extraDevDependencies:
googleapis_auth: '>=1.0.0 <3.0.0'
apis:
- firebaseappdistribution:v1

```

even after keeping only only api, it generate the whole apis