Adding cache eviction and listener for invalidating index field type …

[jainankitk]

…mappings on index deletion/update

Description

This change primarily achieves 2 things:

• Introduces cache eviction logic for ensuring that the field data cache stays bounded
• Adds cluster state listener for invalidating index field type mappings on index deletion/update

Issues Resolved

List any issues this PR will resolve, e.g. Closes [...].

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[deshsidd]

Existing tests still failing. Please take a look @jainankitk

[deshsidd]

Looks like one of the reasons of the build failures is the license headers:

X:/src/main/java/org/opensearch/plugin/insights/core/service/categorizer/IndicesFieldTypeCache.java

[ansjcy]

LGTM, left 1 minor comment.
@jainankitk do you think we should add the cache size as part of the healthcheck API as well?
Also we need to add the license header as caught by the build.

[deshsidd]

if its quick can add unit tests to make sure cache is utilized and evicting properly?

[deshsidd]

LGTM, left 1 minor comment. @jainankitk do you think we should add the cache size as part of the healthcheck API as well? Also we need to add the license header as caught by the build.

would be good to have this as part of the health check APIs in case we see performance issues and need to debug @ansjcy

[deshsidd]

Thanks @jainankitk, LGTM overall. Only pending items seem to be:

1. Build fix
2. Removing the TODO and use the settings
3. Unit tests?