Fix failing OpenSSL tests

[cwperks]

Description

Fixes failing OpenSSLTest errors where the cluster is not able to form because it cannot connect to cluster manager node. This change in main (opensearch-project/OpenSearch#6331) made it so that these lines in ClusterHelper:

final List<NodeInfo> clusterManagerNodes = nodes.stream().filter(n->n.getNode().getRoles().contains(DiscoveryNodeRole.CLUSTER_MANAGER_ROLE)).collect(Collectors.toList());

returned an empty list. By change this line, I was able to fix the test issues.

• Category (Enhancement, New feature, Bug fix, Test fix, Refactoring, Maintenance, Documentation)

Test fix

Check List

• New functionality includes testing
• New functionality has been documented
• Commits are signed per the DCO using --signoff

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