[Manual backport 2.x][Feature] Expose term frequency in Painless script score context (#9081)

[noCharger]

Add the following functions in Painless script score context:

• termfreq
• tf
• totaltermfreq
• sumtotaltermfreq

Each of these maps to a Lucene value source.

Signed-off-by: Louis Chu clingzhi@amazon.com
(cherry picked from commit 5d3633c)

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[opensearch-trigger-bot]

Compatibility status:

Checks if related components are compatible with change ea3c5af

Incompatible components

Incompatible components: [https://github.com/opensearch-project/notifications.git, https://github.com/opensearch-project/index-management.git, https://github.com/opensearch-project/alerting.git, https://github.com/opensearch-project/performance-analyzer.git]

Skipped components

Compatible components

Compatible components: [https://github.com/opensearch-project/geospatial.git, https://github.com/opensearch-project/security.git, https://github.com/opensearch-project/neural-search.git, https://github.com/opensearch-project/security-analytics.git, https://github.com/opensearch-project/sql.git, https://github.com/opensearch-project/job-scheduler.git, https://github.com/opensearch-project/observability.git, https://github.com/opensearch-project/k-nn.git, https://github.com/opensearch-project/anomaly-detection.git, https://github.com/opensearch-project/cross-cluster-replication.git, https://github.com/opensearch-project/asynchronous-search.git, https://github.com/opensearch-project/common-utils.git, https://github.com/opensearch-project/reporting.git, https://github.com/opensearch-project/performance-analyzer-rca.git, https://github.com/opensearch-project/ml-commons.git]

[github-actions]

Gradle Check (Jenkins) Run Completed with:

• RESULT: UNSTABLE ❕
• TEST FAILURES:

      1 org.opensearch.repositories.azure.AzureBlobContainerRetriesTests.testWriteLargeBlob

• URL: https://build.ci.opensearch.org/job/gradle-check/23325/
• CommitID: bc5658d
  Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Merging #9517 (bc5658d) into 2.x (ea3c5af) will decrease coverage by 0.13%.
The diff coverage is 15.11%.

@@             Coverage Diff              @@
##                2.x    #9517      +/-   ##
============================================
- Coverage     70.90%   70.77%   -0.13%     
+ Complexity    57658    57561      -97     
============================================
  Files          4764     4766       +2     
  Lines        272098   272175      +77     
  Branches      40111    40112       +1     
============================================
- Hits         192918   192622     -296     
- Misses        62647    62944     +297     
- Partials      16533    16609      +76     

Files Changed	Coverage Δ
...earch/script/expression/ExpressionScoreScript.java	0.00% <0.00%> (ø)
...arch/script/expression/ExpressionScriptEngine.java	33.99% <ø> (ø)
...earch/example/expertscript/ExpertScriptPlugin.java	0.00% <0.00%> (ø)
...ry/functionscore/TermFrequencyFunctionFactory.java	0.00% <0.00%> (ø)
...n/java/org/opensearch/script/ScoreScriptUtils.java	1.43% <0.00%> (-0.31%)	⬇️
...nsearch/search/lookup/LeafTermFrequencyLookup.java	35.71% <35.71%> (ø)
...c/main/java/org/opensearch/script/ScoreScript.java	56.92% <50.00%> (-1.15%)	⬇️
...nsearch/painless/action/PainlessExecuteAction.java	77.58% <100.00%> (+0.29%)	⬆️
...uery/functionscore/ScriptScoreFunctionBuilder.java	85.36% <100.00%> (ø)
...x/query/functionscore/ScriptScoreQueryBuilder.java	82.27% <100.00%> (ø)

... and 459 files with indirect coverage changes