feat: Test TaskGroupWithTimeout

[Jim-0518]

Description

Summary of Context & Issue

Unit tests cannot accurately simulate continuous time-budget depletion across consecutive TaskGroups or verify Airflow's state machine behavior during timeout failures.
A integration DAG is needed to validate the TaskGroupWithTimeout component under runtime conditions.

Changes

1. Integration DAG: Added test_task_group_with_timeout as an end-to-end testing sandbox.
2. Static Parsing Defenses: Added try...except blocks with AirflowException. Validates that the component successfully blocks nested groups and dynamic mapping during file loading.
3. Budget Depletion Verification: Configured sequential TaskGroups with workloads to prove the component accurately tracks and depletes the shared execution time pool.
4. Teardown Flow Orchestration: Placed the cleanup task outside the group using .as_teardown().

Checklist

Before submitting this PR, please make sure (put X in square brackets):

• I have performed a self-review of my code.
• I have necessary comments in my code, particularly in hard-to-understand areas.
• I have run one-shot tests and provided workload links above if applicable.
• I have made or will make corresponding changes to the doc if needed.