craft-archives does not remove managed repositories that are no longer in the craft.yaml file
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### Bug Description
If you remove a craft-archives managed repository from your *craft.yaml file, it doesn't remove it from the managed system.
The hard part of solving this is figuring out which packages to return to their previous versions, so the best solution right now is to just clean the environment instead.
### To Reproduce
1. Run a pack with the YAML below.
2. Comment out the repositories
3. Run a pack again, and note that the repository is still there.
### part yaml
```shell
package-repositories:
- type: apt
ppa: snappy-devs/snapcraft-daily
```
### Relevant log output
```shell
n/a
```
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