### Apache Airflow version

main (development)

### What happened

It seems [this](https://github.com/apache/airflow/commit/e16207409998b38b91c1f1697557d5c229ed32d1) commit has made the task instance execution date disappear from the task instance tooltip completely:
![image](https://github.com/apache/airflow/assets/18099224/62c9fec5-9e02-4319-93b9-197d25a8b027)
Note the missing `Run: <execution date>` between Task_id and Run_id.
I think there's a problem with the task instance execution date, because it's always `undefined`. In an older version of Airflow (2.4.3), I can see that the tooltip always shows the **current** datetime instead of the actual execution date, which is what the author of the commit identified in the first place I think.

### What you think should happen instead

The tooltip should properly show the task instance's execution date, not the current datetime (or nothing). There's a deeper problem here that causes `ti.execution_date` to be `undefined`.

### How to reproduce

Run the main branch of Airflow, with a simple DAG that finishes a run successfully. Go to the Graph view of a DAG and hover over any completed task with the mouse.

### Operating System

Ubuntu 22.04

### Versions of Apache Airflow Providers

_No response_

### Deployment

Virtualenv installation

### Deployment details

_No response_

### Anything else

_No response_

### Are you willing to submit PR?

- [ ] 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)

from airflow.models.dagwarning import DagWarning
from airflow.models.taskinstance import TaskInstance
from airflow.utils import timezone
from airflow.utils.code_utils import get_python_source
from airflow.utils.helpers import alchemy_to_dict
from airflow.utils.json import WebEncoder
from airflow.utils.sqlalchemy import tuple_in_condition
from airflow.utils.state import State, TaskInstanceState
from airflow.www.forms import DateTimeWithTimezoneField
from airflow.www.widgets import AirflowDateTimePickerWidget
if TYPE_CHECKING:
    from sqlalchemy.orm.session import Session
    from sqlalchemy.sql.operators import ColumnOperators
    from airflow.www.fab_security.sqla.manager import SecurityManager
TI = TaskInstance
def datetime_to_string(value: DateTime | None) -> str | None:
    if value is None:
        return None
    return value.isoformat()
def get_mapped_instances(task_instance, session):
    return session.scalars(
        select(TaskInstance)
        .where(
            TaskInstance.dag_id == task_instance.dag_id,
            TaskInstance.run_id == task_instance.run_id,
            TaskInstance.task_id == task_instance.task_id,
        )
        .order_by(TaskInstance.map_index)
    ).all()
def get_instance_with_map(task_instance, session):