**Apache Airflow version**: 2.0.0a1
**What happened**:

When a task fails on the first try, the log output for additional tries go to the log for the first attempt.

**What you expected to happen**:

The logs should go to the correct log file. For the default configuration, the log filename template is `log_filename_template = {{ ti.dag_id }}/{{ ti.task_id }}/{{ ts }}/{{ try_number }}.log`, so additional numbered `.log` files should be created.

**How to reproduce it**:

Create a test dag:

```
from datetime import timedelta
from airflow import DAG
from airflow.operators.python import PythonOperator
from airflow.utils.dates import days_ago


with DAG(
    dag_id="trynumber_demo",
    default_args={"start_date": days_ago(2), "retries": 1, "retry_delay": timedelta(0)},
    schedule_interval=None,
) as dag:

    def demo_task(ti=None):
        print("Running demo_task, try_number =", ti.try_number)
        if ti.try_number <= 1:
            raise ValueError("Shan't")

    task = PythonOperator(task_id="demo_task", python_callable=demo_task)
```

and trigger this dag:

```
$ airflow dags trigger trynumber_demo
```

then observe that `triggernumber_demo/demo_task/<execution_date>/` only contains 1.log, which contains the full output for 2 runs:

```
[...]
--------------------------------------------------------------------------------
[2020-10-21 13:29:07,958] {taskinstance.py:1020} INFO - Starting attempt 1 of 2
[2020-10-21 13:29:07,959] {taskinstance.py:1021} INFO -
--------------------------------------------------------------------------------
[...]
[2020-10-21 13:29:08,163] {logging_mixin.py:110} INFO - Running demo_task, try_number = 1
[2020-10-21 13:29:08,164] {taskinstance.py:1348} ERROR - Shan't
Traceback (most recent call last):
[...]
ValueError: Shan't
[2020-10-21 13:29:08,168] {taskinstance.py:1392} INFO - Marking task as UP_FOR_RETRY. dag_id=trynumber_demo, task_id=demo_task, execution_date=20201021T122907, start_date=20201021T122907, end_date=20201021T122908
[...]
[2020-10-21 13:29:09,121] {taskinstance.py:1019} INFO -
--------------------------------------------------------------------------------
[2020-10-21 13:29:09,121] {taskinstance.py:1020} INFO - Starting attempt 2 of 2
[2020-10-21 13:29:09,121] {taskinstance.py:1021} INFO -
--------------------------------------------------------------------------------
[...]
[2020-10-21 13:29:09,333] {logging_mixin.py:110} INFO - Running demo_task, try_number = 2
[2020-10-21 13:29:09,334] {python.py:141} INFO - Done. Returned value was: None
[2020-10-21 13:29:09,355] {taskinstance.py:1143} INFO - Marking task as SUCCESS.dag_id=trynumber_demo, task_id=demo_task, execution_date=20201021T122907, start_date=20201021T122909, end_date=20201021T122909
[2020-10-21 13:29:09,404] {local_task_job.py:117} INFO - Task exited with return code 0
```

The `TaskInstance()` created for the run needs to first be refreshed from the database, before setting the logging context.
tests/cli/commands/test_task_command.py
execution_date=DEFAULT_DATE)
        ti_dependent0.refresh_from_db()
        self.assertEqual(ti_dependent0.state, State.FAILED)
        task1_id = 'test_run_dependency_task'
        args1 = ['tasks',
                 'run',
                 '--ignore-all-dependencies',
                 dag_id,
                 task1_id,
                 (DEFAULT_DATE + timedelta(days=1)).isoformat()]
        task_command.task_run(self.parser.parse_args(args1))
        ti_dependency = TaskInstance(
            task=dag.get_task(task1_id),
            execution_date=DEFAULT_DATE + timedelta(days=1))
        ti_dependency.refresh_from_db()
        self.assertEqual(ti_dependency.state, State.FAILED)
        task2_id = 'test_run_dependent_task'
        args2 = ['tasks',
                 'run',
                 '--ignore-all-dependencies',
                 dag_id,
                 task2_id,
                 (DEFAULT_DATE + timedelta(days=1)).isoformat()]
        task_command.task_run(self.parser.parse_args(args2))
        ti_dependent = TaskInstance(
            task=dag.get_task(task2_id),
            execution_date=DEFAULT_DATE + timedelta(days=1))
        ti_dependent.refresh_from_db()
        self.assertEqual(ti_dependent.state, State.SUCCESS)