Deprecate the "Master" nomenclature

[tlfeng]

Is your feature request related to a problem? Please describe.
OpenSearch repository is going to replace the terminology "master"with "cluster manager".
issue: opensearch-project/OpenSearch#472, with the plan for its terminology replacement.

Although the existing usages with "master" will be supported in OpenSearch version 2.x to keep the backwards compatibility, please prepare for the nomenclature change in advance, and replace all the usages with "master" terminology in the code base.
All the OpenSearch REST APIs and settings that contain "master" terminology will be deprecated in 2.0, and alternative usages will be added.

Describe the solution you'd like
Replace the terminology "master" with "cluster manager".

When being compatible with OpenSearch 2.0:

• Replace "master" in code comment and internal variable / class name.
  • public class MasterServiceEventMetricsTests
  • import org.opensearch.performanceanalyzer.metrics.AllMetrics.MasterPendingTaskDimension
  • import org.opensearch.performanceanalyzer.metrics.AllMetrics.MasterPendingValue
  • DiscoveryNode masterNode = discoveryNodes.getMasterNode()
  • public class MasterThrottlingMetricsCollectorTests
  • private static final int MASTER_METRICS_ERRORS
  • import org.opensearch.performanceanalyzer.collectors.MasterServiceEventMetrics
  • import org.opensearch.performanceanalyzer.collectors.MasterThrottlingMetricsCollector

When being compatible with OpenSearch 3.0:

• Replace "master" in the reference to OpenSearch Java API
  (All new APIs below are available in version 2.2)
  • import org.opensearch.cluster.service.MasterService -> import org.opensearch.cluster.service.ClusterManagerService
  • discoveryNodes.getMasterNode() -> discoveryNodes.getClusterManagerNode()
  • DiscoveryNodeRole.MASTER_ROLE -> DiscoveryNodeRole.CLUSTER_MANAGER_ROLE
  • discoBuilder.masterNodeId(nodeId1) -> discoBuilder.clusterManagerNodeId(nodeId1)

Describe alternatives you've considered
None.

Additional context

[dblock]

For 2.0, at a minimum please ensure that the plugin is not calling any deprecated APIs in core or another plugin, and confirm below, then remove the 2.0.0 label. If you have time, do the complete deprecation as described in this issue.

[sruti1312]

PA does not call any deprecated API's in core or another plugin.

[anasalkouz]

@sruti1312 @kaushalmahi12
Is there any remaining effort in this task? if not, please close the issue

[anasalkouz]

@kaushalmahi12 I saw one PR merged. can you close this issue?

[kaushalmahi12]

The changes are merged. Closing the issue.