[Backport 2.x] [Star Tree] [Search] Support for metric aggregations with/without term query

[sandeshkr419]

Description

Backport #15289 to 2.x

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❕ Gradle check result for 9b77ab1: UNSTABLE

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

Attention: Patch coverage is 83.61204% with 49 lines in your changes missing coverage. Please review.

Project coverage is 71.82%. Comparing base (a31e7f2) to head (9b77ab1).
Report is 3 commits behind head on 2.x.

Files with missing lines	Patch %	Lines
...x/datacube/startree/utils/StarTreeQueryHelper.java	71.60%	8 Missing and 15 partials ⚠️
...rch/search/aggregations/metrics/AvgAggregator.java	78.78%	2 Missing and 5 partials ⚠️
...org/opensearch/search/startree/StarTreeFilter.java	93.13%	1 Missing and 6 partials ⚠️
...ensearch/search/startree/StarTreeQueryContext.java	75.00%	2 Missing and 2 partials ⚠️
...main/java/org/opensearch/search/SearchService.java	75.00%	1 Missing and 2 partials ⚠️
...h/index/compositeindex/datacube/DateDimension.java	0.00%	1 Missing ⚠️
...h/index/compositeindex/datacube/ReadDimension.java	0.00%	1 Missing ⚠️
...rch/aggregations/metrics/AvgAggregatorFactory.java	0.00%	1 Missing ⚠️
...rch/aggregations/metrics/MinAggregatorFactory.java	0.00%	1 Missing ⚠️
...regations/metrics/ValueCountAggregatorFactory.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x   #16416      +/-   ##
============================================
- Coverage     71.91%   71.82%   -0.09%     
- Complexity    65221    65250      +29     
============================================
  Files          5308     5312       +4     
  Lines        304350   304646     +296     
  Branches      44268    44324      +56     
============================================
- Hits         218867   218813      -54     
- Misses        67234    67543     +309     
- Partials      18249    18290      +41     

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