[Backport 2.x] Add 2.5 release notes

[opensearch-trigger-bot]

Backport 5f4bef9 from #714

[codecov-commenter]

Codecov Report

Merging #715 (5f4bef9) into 2.x (dd7d0c5) will increase coverage by 0.16%.
The diff coverage is 85.18%.

❗ Current head 5f4bef9 differs from pull request most recent head 23af10a. Consider uploading reports for the commit 23af10a to get more accurate results

@@             Coverage Diff              @@
##                2.x     #715      +/-   ##
============================================
+ Coverage     84.48%   84.64%   +0.16%     
- Complexity     1063     1072       +9     
============================================
  Files           149      151       +2     
  Lines          4332     4345      +13     
  Branches        392      389       -3     
============================================
+ Hits           3660     3678      +18     
+ Misses          492      489       -3     
+ Partials        180      178       -2     

Impacted Files	Coverage Δ
...n/java/org/opensearch/knn/common/KNNConstants.java	93.33% <ø> (ø)
.../main/java/org/opensearch/knn/index/IndexUtil.java	55.73% <ø> (ø)
...va/org/opensearch/knn/index/KNNCircuitBreaker.java	80.00% <0.00%> (+20.00%)	⬆️
.../main/java/org/opensearch/knn/index/KNNMethod.java	100.00% <ø> (ø)
...ava/org/opensearch/knn/index/KNNMethodContext.java	92.50% <ø> (ø)
...java/org/opensearch/knn/index/MethodComponent.java	88.88% <ø> (ø)
...g/opensearch/knn/index/MethodComponentContext.java	91.13% <ø> (ø)
...earch/knn/index/memory/NativeMemoryAllocation.java	82.92% <ø> (ø)
.../java/org/opensearch/knn/index/query/KNNQuery.java	83.33% <ø> (ø)
...org/opensearch/knn/index/query/KNNQueryResult.java	100.00% <ø> (ø)
... and 88 more

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