### Body

We have several tests marked in the code base with `@pytest.mark.quarantined`
It means that the tests are flaky and if fail in CI it does not fail the build.
The goal is to fix the tests and make them stable.

This task is to gather all of them under the same issue instead of dedicated issue per test.

- [x] [TestImpersonation](https://github.com/apache/airflow/blob/bfcae349b88fd959e32bfacd027a5be976fe2132/tests/core/test_impersonation_tests.py#L117)
- [x] [TestImpersonationWithCustomPythonPath](https://github.com/apache/airflow/blob/bfcae349b88fd959e32bfacd027a5be976fe2132/tests/core/test_impersonation_tests.py#L181)
- [x] [test_exception_propagation](https://github.com/apache/airflow/blob/76f81cd4a7433b7eeddb863b2ae6ee59176cf816/tests/jobs/test_local_task_job.py#L772)
- [x] [test_localtaskjob_maintain_heart_rate](https://github.com/apache/airflow/blob/76f81cd4a7433b7eeddb863b2ae6ee59176cf816/tests/jobs/test_local_task_job.py#L402)
- [x] [test_exception_propagation](https://github.com/apache/airflow/blob/4d0fd8ef6adc35f683c7561f05688a65fd7451f4/tests/executors/test_celery_executor.py#L103)
- [x] [test_process_sigterm_works_with_retries](https://github.com/apache/airflow/blob/65010fda091242870a410c65478eae362899763b/tests/jobs/test_local_task_job.py#L770)


### Committer

- [X] I acknowledge that I am a maintainer/committer of the Apache Airflow project.
"""
        Test that ensures that where a task is marked success in the UI
        on_success_callback gets executed
        """
        dag = get_test_dag("test_mark_state")
        with create_session() as session:
            dr = dag.create_dagrun(
                state=State.RUNNING,
                execution_date=DEFAULT_DATE,
                run_type=DagRunType.SCHEDULED,
                session=session,
            )
        task = dag.get_task(task_id="test_mark_success_no_kill")
        ti = dr.get_task_instance(task.task_id)
        ti.refresh_from_task(task)
        job = LocalTaskJob(task_instance=ti, ignore_ti_state=True, executor=SequentialExecutor())
        with timeout(30):
            job.run()  
        ti.refresh_from_db()
        assert (
            "State of this instance has been externally set to success. Terminating instance." in caplog.text
        )
    @pytest.mark.parametrize("signal_type", [signal.SIGTERM, signal.SIGKILL])
    def test_process_os_signal_calls_on_failure_callback(