Remove outdated azd deploy workflow (azure-dev.yml)

The `.github/workflows/azure-dev.yml` workflow ("Deploy with azd") is outdated and should be removed.

Problems:
- It runs an `azd` deployment automatically on every push to `main`, which is not appropriate for this sample.
- It references repository secrets (`secrets.*`) for configuration, which is the old pattern and no longer how these samples are configured.

Please delete `.github/workflows/azure-dev.yml`.