KillTask should return empty inputSource resources

[zachjsh]

Description

This pr fixes a few bugs found with the inputSource security feature.

1. KillUnusedSegmentsTask previously had no definition for the getInputSourceResources, which caused an unsupportedOperationException to be thrown when this task type was submitted with the inputSource security feature enabled. This task type should not require any input source specific resources, so returning an empty set for this task type now.

2. Fixed a bug where when the input source type security feature is enabled, all of the input source type specific resources used where authenticated against:

{"resource": {"name": "EXTERNAL", "type": "{INPUT_SOURCE_TYPE}"}, "action": "READ"}

When they should be instead authenticated against:

{"resource": {"name": "{INPUT_SOURCE_TYPE}", "type": "EXTERNAL"}, "action": "READ"}

3. fixed bug where supervisor tasks were not authenticated against the specific input source types used, if input source security feature was enabled.

This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[abhishekrb19]

Thanks for the fix and addressing the review feedback! LGTM after CI
Should we backport this fix to 26.0 once it's merged to master? (cc: @clintropolis)