[Backport main] add 2.5 release notes

[opensearch-trigger-bot]

Backport fdcb838 from #1268

[codecov-commenter]

Codecov Report

Merging #1274 (aad65b2) into main (7554fcc) will decrease coverage by 35.59%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##               main    #1274       +/-   ##
=============================================
- Coverage     98.35%   62.76%   -35.60%     
=============================================
  Files           344       10      -334     
  Lines          8946      658     -8288     
  Branches        569      119      -450     
=============================================
- Hits           8799      413     -8386     
- Misses          142      192       +50     
- Partials          5       53       +48     

Flag	Coverage Δ
query-workbench	62.76% <ø> (?)
sql-engine	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...l/expression/function/DefaultFunctionResolver.java
...on/window/aggregation/AggregateWindowFunction.java
...nsearch/sql/sql/parser/AstHavingFilterBuilder.java
...ensearch/storage/system/OpenSearchSystemIndex.java
.../opensearch/sql/protocol/response/QueryResult.java
...ensearch/sql/planner/physical/ProjectOperator.java
...ilter/lucene/relevance/SimpleQueryStringQuery.java
...main/java/org/opensearch/sql/executor/QueryId.java
...opensearch/sql/expression/span/SpanExpression.java
...s/planner/logical/PrometheusLogicalMetricScan.java
... and 344 more

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[penghuo]

BWC test failed. opensearch-project/OpenSearch#5815