Add a sanity check before bumping provider version

### Body

Recently we ran into an issue while releasing providers, that if the changelog already had the "to be released" version of the provider, the repo would go into a slightly weird state while updating the documentation.

Some details from a DM:

> the issue is that if I am marking release as 9.3.0 but 9.3.0 exist in the change log then the output is as I showed you.. all tagging is lost.
ideally what we need to have is for the process to alert me that i asked to cut 9.3.0 but it's already exist. that way I can go and manually fix the change log then resume from that point

The command that requires updates (for amazon)
```
breeze release-management prepare-provider-documentation amazon
```

### Committer

- [x] I acknowledge that I am a maintainer/committer of the Apache Airflow project.

Start with the `breeze release-management prepare-provider-documentation amazon` command and trace the provider release-preparation flow that checks the changelog and updates documentation. Reproduce the case where the requested version already exists in the changelog, then make completion include a clear alert without losing release tags or leaving the repository in a corrupted state.

Written by the indexing model from the issue text.