Version bump to opensearch-3.0.0-alpha1 and replaced usage of deprecated classes

[aggarwalShivani]

Description

Updated to opensearch-3.0.0-alpha1 and fixed usage of classes that are refactored/replaced in latest opensearch.

Changes:

• Fixed imports for classes moved from org.opensearch.action.support.master to org.opensearch.action.support.clustermanager
• Fixed imports for classes moved from org.opensearch.client to org.opensearch.transport.client
• Replaced usage of deprecated classes (MasterNodeRequest, TransportMasterNodeAction) and methods (masterOperation()) etc by their alternatives (ClusterManagerNodeRequest, TransportClusterManagerNodeAction, clusterManagerOperation()).

Related Issues

Resolves #1503

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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[ankitkala]

Security tests are failing. I see that they've not yet bumped up the version to 3.0. I'm okay to merge this change for now.