### Apache Airflow version

Other Airflow 2 version (please specify below)

### What happened

Greetings!
Recently I’ve faced a problem. It seems that assigning object, which can’t be serialized to JSON, to the dag_run.conf dict cause critical errors with UI.
After executing code example in "How to reproduce": 
Grid representation of the DAG breaks with following result:
<img width="800" alt="Pasted Graphic" src="https://github.com/apache/airflow/assets/79107237/872ccde5-500f-4484-a36c-dce6b7112286">
Browse -> DAG Runs also becomes unavailable.
<img width="800" alt="Pasted Graphic 1" src="https://github.com/apache/airflow/assets/79107237/b4e3df0c-5324-41dd-96f3-032e706ab7a9">
Dag itself continues to work correctly, this affects only UI graph and dagrun/list/
I suggest to use custom dictionary with restriction on setting non json values.

### What you think should happen instead

Raise an error

### How to reproduce

Execute following task. 
Composer 2 version 2.4.2
Airflow version 2.5.3
```
@task 
def test_task(**context):
    context['dag_run'].conf["test"] = np.int64(1234)
```

### Operating System

Ubuntu 20.04.6 LTS

### Versions of Apache Airflow Providers

_No response_

### Deployment

Google Cloud Composer

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [X] Yes I am willing to submit a PR!

### Code of Conduct

- [X] I agree to follow this project's [Code of Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)

return
        if self.clear_number > 0:
            return
        if not finished_tis:
            return
        try:
            dag = self.get_dag()
            if not dag.timetable.periodic:
                
                return
            try:
                first_start_date = min(ti.start_date for ti in finished_tis if ti.start_date)
            except ValueError:  
                pass
            else:
                
                
                
                
                
                data_interval_end = dag.get_run_data_interval(self).end
                true_delay = first_start_date - data_interval_end
                if true_delay.total_seconds() > 0:
                    Stats.timing(
                        f"dagrun.{dag.dag_id}.first_task_scheduling_delay", true_delay, tags=self.stats_tags
                    )
                    Stats.timing("dagrun.first_task_scheduling_delay", true_delay, tags=self.stats_tags)
        except Exception:
            self.log.warning("Failed to record first_task_scheduling_delay metric:", exc_info=True)
    def _emit_duration_stats_for_finished_state(self):