Add support for restoring from snapshot with search replicas

[vinaykpud]

Description

In this PR we are adding,

1. Support for restoring search replicas from a snapshot taken with search replica
2. Add validations to ensure compatibility between DOCUMENT and SEGMENT replication type while snapshot restoration. Following are the allowed rules:

• Snapshots taken when the replication type is DOCUMENT can be restored to DOCUMENT or SEGMENT types. If we are restoring to SEGMENT type more search replicas can be added.
• Snapshots taken when the replication type is SEGMENT and without any search replicas can be restored to DOCUMENT or SEGMENT types. If we are restoring to SEGMENT type more search replicas can be added.
• Snapshots taken when the replication type is SEGMENT and with search replicas can be restored to DOCUMENT or SEGMENT types. If we are restoring to SEGMENT type more search replicas can be added. If we are restoring to DOCUMENT type search replica count must be set to 0 in the settings.

Related Issues

Resolves #15532
Related #15306

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 7556720: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[mch2]

nitpicks -

Lets pass a ReplicationType here and parse in the caller and use ReplicationType. DOCUMENT.equals(replicationType)

is snapshotIndexMetadata the metadata inside the snapshot? Passing that as restoreReplicationType is a bit confusing. How about snapshottedMetadata and updatedMetadata ?

[vinaykpud]

snapshotIndexMetadata contains metadata of snapshot and whatever setting user is trying to override. So basically its a metadata which will be applied for resulting restored index.

[vinaykpud]

do you mean like this?

private void validateReplicationTypeRestoreSettings(IndexMetadata snapshottedMetadata, IndexMetadata updatedMetadata)

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✅ Gradle check result for 641a804: SUCCESS

[codecov]

Codecov Report

Attention: Patch coverage is 63.63636% with 4 lines in your changes missing coverage. Please review.

Project coverage is 71.84%. Comparing base (6020c58) to head (641a804).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
.../java/org/opensearch/snapshots/RestoreService.java	50.00%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #16111      +/-   ##
============================================
- Coverage     71.88%   71.84%   -0.05%     
+ Complexity    64496    64475      -21     
============================================
  Files          5291     5291              
  Lines        301668   301679      +11     
  Branches      43576    43579       +3     
============================================
- Hits         216863   216747     -116     
- Misses        67031    67123      +92     
- Partials      17774    17809      +35     

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