Made NestedAggregate inherit from AggregateBase

[nhtruong]

Description

Made NestedAggregate inherit from AggregateBase instead of SingleBucketAggregateBase to resolve doc_count conflict where the schema is a union of 2 different objects with conflicting requirement for properties doc_type (one says it's optional while the other says it's required)

This conflict is causing an error on the Node.js client generator.

• Tests have already been provided in a previous commit that updated this schema.

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[github-actions]

Changes Analysis

Commit SHA: dd7df64
Comparing To SHA: e95e7d3

API Changes

Summary

└─┬Components
  └─┬_common.aggregations:NestedAggregate
    └─┬ALLOF
      └──[🔀] $ref (32342:13)❌ 

Document Element	Total Changes	Breaking Changes
components	1	2

• ❌ BREAKING Changes: 2 out of 1
• Modifications: 1
• Breaking Modifications: 1

Report

The full API changes report is available at: https://github.com/opensearch-project/opensearch-api-specification/actions/runs/11444817573/artifacts/2083605149

API Coverage

	Before	After	Δ
Covered (%)	588 (57.59 %)	588 (57.59 %)	0 (0 %)
Uncovered (%)	433 (42.41 %)	433 (42.41 %)	0 (0 %)
Unknown	29	29	0

[github-actions]

Spec Test Coverage Analysis

Total	Tested
504	317 (62.9 %)