CascadingReindexingTemplate update to drop support for native engine + nuke ReindexingIOConfigRule

[capistrant]

Description

CascadingReindexingTemplate usage in autocompaction supervisors was originally going to support both native and msq engine. However, once we added the ability to use virtual columns to extract json fields for ReindexingDeletionRules based on nested fields, we created functionality that could only work for MSQ but not native. This fracture could keep growing as functionality is added, and instead of trying to manage it, I think it is best to cut the cord on supporting native for this template and instead push forward with just MSQ support. A lot of the community energy is around driving adoption of MSQ over native engine for compaction so I think this makes sense long term.

As a result of this decision, theReindexingIOConfigRule is no longer needed as all it existed for was setting dropExisting to true for native so you could create tombstones.

Release note

N/A, but this will change the release not for Druid 37 for the cascading reindexing feature in general.

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This PR has:

• been self-reviewed.
• 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.

[capistrant]

thanks for the review, @kfaraz !