Fixing badly written test for user impersonation

[amoghrajesh]

There can be a possibility that the command can be run with python3 instead of python:

{"timestamp":"2024-12-03T10:00:00Z","level":"info","event":"Running command","command":["sudo","-E","-H","-u","airflowuser","/usr/local/bin/python3","-c","from airflow.sdk.execution_time.task_runner import main; main()"],"logger":"task"}

Asserting better to avoid issues like:

____________________ test_task_run_with_user_impersonation _____________________
[gw0] linux -- Python 3.12.11 /usr/local/bin/python3
task-sdk/tests/task_sdk/execution_time/test_task_runner.py:689: in test_task_run_with_user_impersonation
    assert "python -c" in actual_cmd[5] + " " + actual_cmd[6]
E   AssertionError: assert 'python -c' in (('/usr/local/bin/python3' + ' ') + '-c')

Fixes https://github.com/apache/airflow/actions/runs/15752220682/job/44400018685

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[potiuk]

This one is fixed but we have a "baseball game" another issue.