Updates to `health.yaml` (#310)

- Run health workflow on all packages if it is changed
- Specify Flutter packages in the repo, to only have a single workflow
file
- Compare to last published version in breaking check.

This is a breaking change, as the `use-flutter` argument is not existing
anymore. After landing this, all `dart-lang/` repos will have to be
updated. As part of that update, we should maybe have the `health.yaml`s
depend on a hash instead of the `main` branch.

---

- [x] I’ve reviewed the contributor guide and applied the relevant
portions to this PR.

<details>
  <summary>Contribution guidelines:</summary><br>

- See our [contributor
guide](https://github.com/dart-lang/.github/blob/main/CONTRIBUTING.md)
for general expectations for PRs.
- Larger or significant changes should be discussed in an issue before
creating a PR.
- Contributions to our repos should follow the [Dart style
guide](https://dart.dev/guides/language/effective-dart) and use `dart
format`.
- Most changes should add an entry to the changelog and may need to [rev
the pubspec package
version](https://github.com/dart-lang/sdk/blob/main/docs/External-Package-Maintenance.md#making-a-change).
- Changes to packages require [corresponding
tests](https://github.com/dart-lang/.github/blob/main/CONTRIBUTING.md#Testing).

Note that many Dart repos have a weekly cadence for reviewing PRs -
please allow for some latency before initial review feedback.
</details>

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Co-authored-by: Devon Carew <devoncarew@google.com>