[AIRFLOW-5419] - Use sudo to kill cleared tasks when running with impersonation

[bharathpalaksha]

Marking task failed doesn't kill task, when it is run through impersonation(run_as_user)

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Jira

• My PR addresses the following Airflow Jira issues and references them in the PR title.

Description

• When a dag is run through impersonation 'run_as_user'. Tasks won't get killed when a SIGTERM is issued either by marking it failed explicitly or by scheduler.

Tests

• Existing test cases should take care as it is already covered and this is more of linux process level defect

Commits

• My commits all reference Jira issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Documentation

• [ ]

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@dd36d90). Click here to learn what that means.
The diff coverage is 33.33%.

@@            Coverage Diff            @@
##             master    #6026   +/-   ##
=========================================
  Coverage          ?   80.03%           
=========================================
  Files             ?      594           
  Lines             ?    34751           
  Branches          ?        0           
=========================================
  Hits              ?    27813           
  Misses            ?     6938           
  Partials          ?        0

Impacted Files	Coverage Δ
airflow/utils/helpers.py	77.97% <33.33%> (ø)

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[bharathpalaksha]

@ashb please check the comments in response to your review comment and also have addresses the things pointed out

[bharathpalaksha]

@ashb please look into this