### 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.
executor = configuration.conf.get("core", "executor")
        sql_alchemy_conn = self.anonymizer.process_url(
            configuration.conf.get("database", "SQL_ALCHEMY_CONN", fallback="NOT AVAILABLE")
        )
        dags_folder = self.anonymizer.process_path(
            configuration.conf.get("core", "dags_folder", fallback="NOT AVAILABLE")
        )
        plugins_folder = self.anonymizer.process_path(
            configuration.conf.get("core", "plugins_folder", fallback="NOT AVAILABLE")
        )
        base_log_folder = self.anonymizer.process_path(
            configuration.conf.get("logging", "base_log_folder", fallback="NOT AVAILABLE")
        )
        remote_base_log_folder = self.anonymizer.process_path(
            configuration.conf.get("logging", "remote_base_log_folder", fallback="NOT AVAILABLE")
        )
        return [
            ("version", airflow_version),
            ("executor", executor),
            ("task_logging_handler", self._task_logging_handler()),
            ("sql_alchemy_conn", sql_alchemy_conn),
            ("dags_folder", dags_folder),
            ("plugins_folder", plugins_folder),
            ("base_log_folder", base_log_folder),
            ("remote_base_log_folder", remote_base_log_folder),
        ]
    @property
    def _system_info(self):