Fix example_bash_decorator DAG (apache#56020)

The ``example_bash_decorator`` was broken since it relied on the Airflow source code path.

Before:

```
{"timestamp":"2025-09-23T11:44:15.971920Z","level":"info","event":"Running command: ['/usr/bin/bash', '-c', 'stat']","logger":"airflow.task.hooks.airflow.providers.standard.hooks.subprocess.SubprocessHook","filename":"subprocess.py","lineno":88}
{"timestamp":"2025-09-23T11:44:15.995649Z","level":"info","event":"Output:","logger":"airflow.task.hooks.airflow.providers.standard.hooks.subprocess.SubprocessHook","filename":"subprocess.py","lineno":99}
{"timestamp":"2025-09-23T11:44:15.999568Z","level":"info","event":"stat: missing operand","logger":"airflow.task.hooks.airflow.providers.standard.hooks.subprocess.SubprocessHook","filename":"subprocess.py","lineno":106}
{"timestamp":"2025-09-23T11:44:15.999669Z","level":"info","event":"Try 'stat --help' for more information.","logger":"airflow.task.hooks.airflow.providers.standard.hooks.subprocess.SubprocessHook","filename":"subprocess.py","lineno":106}
{"timestamp":"2025-09-23T11:44:16.000278Z","level":"info","event":"Command exited with return code 1","logger":"airflow.task.hooks.airflow.providers.standard.hooks.subprocess.SubprocessHook","filename":"subprocess.py","lineno":110}
{"timestamp":"2025-09-23T11:44:16.000884Z","level":"error","event":"Task failed with exception","logger":"task","filename":"task_runner.py","lineno":972,"error_detail":[{"exc_type":"AirflowException","exc_value":"Bash command failed. The command returned a non-zero exit code 1.","exc_notes":[],"syntax_error":null,"is_cause":false,"frames":[{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/execution_time/task_runner.py","lineno":920,"name":"run"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/execution_time/task_runner.py","lineno":1307,"name":"_execute_task"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/bases/operator.py","lineno":416,"name":"wrapper"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/providers/standard/decorators/bash.py","lineno":100,"name":"execute"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/bases/operator.py","lineno":416,"name":"wrapper"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/bases/decorator.py","lineno":252,"name":"execute"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/sdk/bases/operator.py","lineno":416,"name":"wrapper"},{"filename":"/home/airflow/.local/lib/python3.12/site-packages/airflow/providers/standard/operators/bash.py","lineno":232,"name":"execute"}],"is_group":false,"exceptions":[]}]}
{"timestamp":"2025-09-23T11:44:16.025800Z","level":"info","event":"Task instance in failure state","logger":"task.stdout"}
{"timestamp":"2025-09-23T11:44:16.025944Z","level":"info","event":"Task start","logger":"task.stdout"}
{"timestamp":"2025-09-23T11:44:16.026033Z","level":"info","event":"Task:<Task(_BashDecoratedOperator): get_file_stats>","logger":"task.stdout"}
{"timestamp":"2025-09-23T11:44:16.026135Z","level":"info","event":"Failure caused by Bash command failed. The command returned a non-zero exit code 1.","logger":"task.stdout"}
```

After:

```
[2025-09-24 02:12:47] INFO - Task instance is in running state
[2025-09-24 02:12:47] INFO -  Previous state of the Task instance: TaskInstanceState.QUEUED
[2025-09-24 02:12:47] INFO - Current task name:get_file_stats
[2025-09-24 02:12:47] INFO - Dag name:example_bash_decorator
[2025-09-24 02:12:47] INFO - Tmp dir root location: /tmp
[2025-09-24 02:12:47] INFO - Running command: ['/usr/bin/bash', '-c', 'stat /opt/airflow/airflow-core/src/airflow/example_dags/standard/example_bash_decorator.py']
[2025-09-24 02:12:47] INFO - Output:
[2025-09-24 02:12:47] INFO -   File: /opt/airflow/airflow-core/src/airflow/example_dags/standard/example_bash_decorator.py
[2025-09-24 02:12:47] INFO -   Size: 3867      	Blocks: 8          IO Block: 4096   regular file
[2025-09-24 02:12:47] INFO - Device: 0,34	Inode: 2057958327228072012  Links: 1
[2025-09-24 02:12:47] INFO - Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
[2025-09-24 02:12:47] INFO - Access: 2025-09-24 01:12:17.366858270 +0000
[2025-09-24 02:12:47] INFO - Modify: 2025-09-24 01:08:56.992964565 +0000
[2025-09-24 02:12:47] INFO - Change: 2025-09-24 01:08:56.992964565 +0000
[2025-09-24 02:12:47] INFO -  Birth: -
[2025-09-24 02:12:47] INFO - Command exited with return code 0
[2025-09-24 02:12:47] INFO - Pushing xcom ti=RuntimeTaskInstance(id=UUID('01997947-a73f-77ea-a2d0-a4d63f57bf03'), task_id='get_file_stats', dag_id='example_bash_decorator', run_id='manual__2025-09-24T01:12:42.913441+00:00', try_number=1, dag_version_id=UUID('01997947-6324-771c-ae0e-4a01d869e171'), map_index=-1, hostname='72ace79a9422', context_carrier={}, task=<Task(_BashDecoratedOperator): get_file_stats>, bundle_instance=LocalDagBundle(name=example_dags), max_tries=0, start_date=datetime.datetime(2025, 9, 24, 1, 12, 47, 289149, tzinfo=datetime.timezone.utc), end_date=None, state=<TaskInstanceState.RUNNING: 'running'>, is_mapped=False, rendered_map_index=None)
[2025-09-24 02:12:47] INFO - Task instance in success state
[2025-09-24 02:12:47] INFO -  Previous state of the Task instance: TaskInstanceState.RUNNING
[2025-09-24 02:12:47] INFO - Task operator:<Task(_BashDecoratedOperator): get_file_stats>
```

Author: kaxil

providers/standard/src/airflow/providers/standard/example_dags/example_bash_decorator.py

@@ -92,21 +92,14 @@ def make_dynamic_dirs(new_dirs: str) -> str:
     # [END howto_decorator_bash_parametrize]
 
     # [START howto_decorator_bash_build_cmd]
-    def _get_files_in_cwd() -> list[str]:
-        from pathlib import Path
-
-        dir_contents = Path.cwd().glob("airflow-core/src/airflow/example_dags/*.py")
-        files = [str(elem) for elem in dir_contents if elem.is_file()]
-
-        return files
-
     @task.bash
     def get_file_stats() -> str:
+        from pathlib import Path
         from shlex import join
 
-        files = _get_files_in_cwd()
-        files = files if files else ["."]
-        cmd = join(["stat", *files])
+        # Get stats of the current DAG file itself
+        current_file = str(Path(__file__))
+        cmd = join(["stat", current_file])
 
         return cmd