[8.19] [Entity Store v1] Update docs to comply with OpenAPI Specification (OAS) (#262526)

[kubasobon]

Backport

This will backport the following commits from main to 8.19:

• [Entity Store v1] Update docs to comply with OpenAPI Specification (OAS) (#262526)

Note: Only includes changes for APIs that exist on 8.19 (excludes delete_entity, upsert_entity, upsert_entities_bulk, GenericEntity, and other schemas not present on this branch). Generated files (.gen.ts, bundled yamls, OAS output) still need regeneration after bootstrap.

Questions ?

Please refer to the Backport tool documentation

[elasticmachine]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: bb62d3c

Failed CI Steps

• FTR Configs #72

Test Failures

• [job] [logs] FTR Configs #72 / Profiling API tests feature_controls.spec.ts cloud Loading profiling data Profiling feature controls returns ok for users with access to profiling APIs

Metrics [docs]

✅ unchanged

cc @kubasobon