Fix flaky tests in org.opensearch.cluster.routing.remote.RemoteRoutingTableServiceTests

[gaobinlong]

Description

This PR fixes the flaky test cases in org.opensearch.cluster.routing.remote.RemoteRoutingTableServiceTests, the failure is caused by that randomInt(1000) can generate 0 but 0 is not valid for the index setting index.number_of_shards.

By the way, some unused code in this test file are also deleted.

Changelog is not needed, backport to 2.x is needed.

Related Issues

#14263

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 c1ffe62: 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?

[gaobinlong]

❌ Gradle check result for c1ffe62: 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?

Known issue:#12788

[github-actions]

❌ Gradle check result for 9415706: 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?

[dblock]

❌ Gradle check result for 9415706: 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?

org.opensearch.cluster.coordination.AwarenessAttributeDecommissionIT.testConcurrentDecommissionAction

#12197

org.opensearch.indices.IndicesRequestCacheIT.testCacheCleanupWithDefaultSettings {p0={"opensearch.experimental.feature.pluggable.caching.enabled":"false"}}

#13711

[github-actions]

❌ Gradle check result for 9415706: 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?

[gaobinlong]

❌ Gradle check result for 9415706: 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?

Known issue:#1703

[github-actions]

❌ Gradle check result for b5f2a77: 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?

[github-actions]

❌ Gradle check result for 73a8470: 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?

[github-actions]

❌ Gradle check result for 73a8470: 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?

[github-actions]

✅ Gradle check result for a4b4d31: SUCCESS

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.61%. Comparing base (b15cb0c) to head (a4b4d31).
Report is 432 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #14264      +/-   ##
============================================
+ Coverage     71.42%   71.61%   +0.19%     
- Complexity    59978    62023    +2045     
============================================
  Files          4985     5118     +133     
  Lines        282275   291829    +9554     
  Branches      40946    42188    +1242     
============================================
+ Hits         201603   208983    +7380     
- Misses        63999    65583    +1584     
- Partials      16673    17263     +590     

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