TaskGroup “Downstream Clear” doesn’t affect all failed tasks inside the group

### Apache Airflow version

3.1.0

### If "Other Airflow 2/3 version" selected, which one?

_No response_

### What happened?

When I click Downstream Clear on a TaskGroup that contains multiple failed tasks,
only a subset of tasks inside the group appear in the “affected tasks” dialog.
However, when I click Run → failed only from the DAG Run view,
all failed tasks are properly selected and cleared.

So, the “Downstream Clear” behavior seems inconsistent between the DAG Run and TaskGroup levels.

### What you think should happen instead?

_No response_

### How to reproduce

Create a DAG with many tasks inside a TaskGroup A. Run the DAG and let several tasks in the group fail. Then click the TaskGroup and choose Downstream Clear — only some failed tasks appear in the affected tasks list. In contrast, clicking the DAG Run and choosing Run → failed only correctly selects all failed tasks.

### Operating System

Ubuntu 22.04

### Versions of Apache Airflow Providers

_No response_

### Deployment

Official Apache Airflow Helm Chart

### 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)

Start by reproducing the TaskGroup Downstream Clear flow with several failed tasks, then compare its affected-tasks result with Run → failed only from the DAG Run view. Done means both paths identify and clear all failed tasks inside the group; the issue names no files or tests, so locate the relevant UI action and add coverage for this comparison.

Written by the indexing model from the issue text.