[GRPC] Update GRPC APIs to use latest opensearch-protobufs:0.3.0 jar and various javadocs fixes

[karenyrx]

This PR is a prerequisite for #17888.

Description

1. Pull in latest protobuf changes (opensearch-project/opensearch-protobufs@0.2.0...0.3.0 ) -> which consequently required a bunch of changes to existing document APIs to compile properly
2. Fix some java docs in plugins/transport-grpc

Related Issues

Resolves #[Issue number to be closed when this PR is merged]
#16783
#16784

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 190448a: FAILURE

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[github-actions]

❕ Gradle check result for 190448a: UNSTABLE

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[codecov]

Codecov Report

Attention: Patch coverage is 96.42857% with 1 line in your changes missing coverage. Please review.

Project coverage is 72.49%. Comparing base (1628152) to head (dab222f).
Report is 14 commits behind head on main.

Files with missing lines	Patch %	Lines
...ponse/document/common/DocumentFieldProtoUtils.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #17895      +/-   ##
============================================
+ Coverage     72.43%   72.49%   +0.05%     
- Complexity    66789    66792       +3     
============================================
  Files          5449     5454       +5     
  Lines        309085   309119      +34     
  Branches      44979    44984       +5     
============================================
+ Hits         223899   224084     +185     
+ Misses        66906    66727     -179     
- Partials      18280    18308      +28     

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[github-actions]

❌ Gradle check result for d7f48ab: FAILURE

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❌ Gradle check result for dab222f: FAILURE

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[github-actions]

❕ Gradle check result for dab222f: UNSTABLE

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