SOLR-16396: Migrate remaining GET /config/{component} sections to JAX-RS

[jaykay12]

https://issues.apache.org/jira/browse/SOLR-16396

Description

Migrate remaining GET /config/{component} sections to JAX-RS

Solution

This will be a follow-up PR after: #5168

Will convert this from Draft -> ready-for-review once that PR is merged.

With this PR merged, all GET config sections will get be fully JAX-RS compatible.

Tests

TBA

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
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• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide
• I have added a changelog entry for my change

[epugh]

Found a bug while reviewing this against `dev-docs/apis-v2-conventions.adoc`: `circuitBreaker`, `initParams`, `listener`, and `updateRequestProcessorChain` are declared without `REQUIRE_NAME` in `SolrConfig`'s plugin registry, so `SolrConfig#writeMap` serializes them as a `List` rather than a name-keyed `Map`. `GetConfig#filterByComponentName`'s unconditional `(Map)` cast then throws a `ClassCastException` for any by-name lookup against these sections — reachable both via v1's `componentName` query param (pre-existing bug, predates this PR) and the new v2 `GET /config/{component}/{componentName}` path this PR adds. That surfaces as an uncaught 500 instead of the documented NOT_FOUND/404 convention.

Reproduced with a throwaway test: `GET .../config/circuitBreaker/x` 500'd with the ClassCastException before this fix, returns a clean 404 after.

Pushed a fix:

• `filterByComponentName` now checks the section's shape and throws a clean `NOT_FOUND` when by-name filtering doesn't apply (fixes the v1 path too).
• Dropped those 4 non-named sections from the v2 by-name `@Path` regex, since a route that can never match by name isn't useful API surface.
• Also noticed `cache` has the same `REQUIRE_NAME + MULTI_OK` shape as the other sections this PR already pluralizes (`listener`→`listeners`, `queryParser`→`queryParsers`, etc.) but was left singular — renamed to `caches` for consistency.

All existing tests pass (`GetConfigTest`, `GetConfigSolrCloudTest`, `V2ConfigAPIMappingTest`, `TestSolrConfigHandler`, `TestSolrConfigHandlerCloud`).