Add support for Search replica to return segrep stats

[vinaykpud]

Description

In this PR we are adding,

• Support for search replica to return its segrep stats
• This doesn't change any of the existing implementation stats calculation for the regular replicas
• For search replicas we are just calculating the stats using the difference between the computed checkpoint in the shard and latest pulled checkpoint from the remote store. So this stat will help to know if any problematic replications in search replica which is taking longer.

Related Issues

Resolves #15534 Related #15306

Check List

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

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[github-actions[bot]]

:x: Gradle check result for d01aef3b9f139227832cdebed702079599f1d0f9: null

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?