feat(search): unified entity index

[david-leifker]

Introduce a new unified entity index which consolidates entity indices (100+) into a few indices. It will eventually also replace the system metadata index. This is disabled by default and only contains code for the write path at this time.

Major Features

• Unified Search Indexes: Partial implementation supporting v3 entity index management, settings/mappings, and dual writes (current v2 & v3)
• Search Index Groups: New entity registry configuration for managing multiple search index entity groups

Key Components Added

• MultiEntityMappingsBuilder - Unified mapping generation
• UpdateIndicesV2Strategy & UpdateIndicesV3Strategy - Index update strategies
• SearchableAnnotationValidator - Validation for search annotations
• DelegatingMappingsBuilder & DelegatingSettingsBuilder - Delegation patterns

Configuration Changes

• New entity registry YAML configuration for search index groups

[codecov]

Codecov Report

❌ Patch coverage is 81.40663% with 460 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...edin/metadata/service/UpdateIndicesV2Strategy.java	58.44%	57 Missing and 7 partials ⚠️
...elasticsearch/index/entity/v3/FieldTypeMapper.java	65.16%	25 Missing and 6 partials ⚠️
...elasticsearch/index/DelegatingSettingsBuilder.java	54.83%	25 Missing and 3 partials ⚠️
...rch/elasticsearch/indexbuilder/ESIndexBuilder.java	63.15%	22 Missing and 6 partials ⚠️
...elasticsearch/index/DelegatingMappingsBuilder.java	83.22%	19 Missing and 8 partials ⚠️
...ch/index/entity/v3/MultiEntityMappingsBuilder.java	93.75%	11 Missing and 15 partials ⚠️
...inkedin/metadata/service/UpdateIndicesService.java	72.34%	15 Missing and 11 partials ⚠️
...tadata/search/elasticsearch/update/ESWriteDAO.java	31.03%	20 Missing ⚠️
...ata/search/elasticsearch/ElasticSearchService.java	24.00%	19 Missing ⚠️
...icsearch/index/entity/v3/AspectMappingBuilder.java	89.70%	3 Missing and 11 partials ⚠️
... and 31 more

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[alwaysmeticulous]

✅ Meticulous spotted 0 visual differences across 964 screens tested: view results.

Meticulous evaluated ~8 hours of user flows against your PR.

_{Expected differences? Click here. Last updated for commit 35bf515. This comment will update as new commits are pushed.}

[codecov]

Bundle Report

Bundle size has no change ✅