### Body

We had an issue where extra link class (`AIPlatformConsoleLink`) was removed in [PR](https://github.com/apache/airflow/pull/26836) without removing the class from the `provider.yaml` extra links this resulted in web server exception as shown in https://github.com/apache/airflow/pull/28449


**The Task:**
Add validation that classes of extra-links in provider.yaml are importable

### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
system_path = os.environ.get("PATH", "").split(os.pathsep)
        airflow_home = self.anonymizer.process_path(configuration.get_airflow_home())
        system_path = [self.anonymizer.process_path(p) for p in system_path]
        python_path = [self.anonymizer.process_path(p) for p in sys.path]
        airflow_on_path = any(os.path.exists(os.path.join(path_elem, "airflow")) for path_elem in system_path)
        return [
            ("airflow_home", airflow_home),
            ("system_path", os.pathsep.join(system_path)),
            ("python_path", os.pathsep.join(python_path)),
            ("airflow_on_path", str(airflow_on_path)),
        ]
    @property
    def _providers_info(self):