[Derived Field] Integration tests for derived fields (opensearch-proj…

…ect#13721)

* Integration test for derived fields

* tests derived fields when defined in index mappings
* tests derived fields when defined in query
* tests mappings and settings updates for derived fields
* tests index and search analyzer applicability on derived fields
* tests query string

Signed-off-by: Rishabh Maurya <rishabhmaurya05@gmail.com>

* rename source_indexed_field to prefilter_field

Signed-off-by: Rishabh Maurya <rishabhmaurya05@gmail.com>

* Add entry to CHANGELOG

Signed-off-by: Rishabh Maurya <rishabhmaurya05@gmail.com>

---------

Signed-off-by: Rishabh Maurya <rishabhmaurya05@gmail.com>
(cherry picked from commit c49eca4)

CHANGELOG.md

@@ -21,6 +21,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Move Remote Store Migration from DocRep to GA and modify remote migration settings name ([#14100](https://github.com/opensearch-project/OpenSearch/pull/14100))
 - [Remote State] Add async remote state deletion task running on an interval, configurable by a setting ([#13995](https://github.com/opensearch-project/OpenSearch/pull/13995))
 - Add remote routing table for remote state publication with experimental feature flag ([#13304](https://github.com/opensearch-project/OpenSearch/pull/13304))
+- Derived field object type support ([#13720](https://github.com/opensearch-project/OpenSearch/pull/13720))
 
 ### Dependencies
 - Bump `com.github.spullara.mustache.java:compiler` from 0.9.10 to 0.9.13 ([#13329](https://github.com/opensearch-project/OpenSearch/pull/13329), [#13559](https://github.com/opensearch-project/OpenSearch/pull/13559))