HDDS-8363. Make SCM Ratis roles available in /prom endpoint

[mladjan-gadzic]

What changes were proposed in this pull request?

Add SCM HA metrics to /jmx and /prom endpoints.

{
"name": "Hadoop:service=StorageContainerManager,name=SCMHAMetrics",
"modelerType": "SCMHAMetrics",
"tag.NodeId": "3c8c82f5-524a-41f4-beea-8dcd868fbf91",
"tag.Hostname": "bca1fb37b8aa",
"SCMHALeaderState": 1
}

# TYPE scmha_metrics_scmha_leader_state gauge
scmha_metrics_scmha_leader_state{nodeid="3c8c82f5-524a-41f4-beea-8dcd868fbf91",hostname="bca1fb37b8aa"} 1

Similar PR: #4140.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-8363

How was this patch tested?

• unit
• integration
• manual

Steps for manual test:

• start Docker cluster for HA environment ozone-ha and wait for it to be ready
• check if SCM HA metrics are initialized correctly
• stop SCM leader node and wait for new leader to be elected
• check if SCM HA metrics are updated correctly

[xBis7]

Thanks @mladjan-gadzic for working on this. I've left a few comments inline.

[mladjan-gadzic]

@xBis7 thanks for the review!

[adoroszlai]

Thanks @mladjan-gadzic for the patch, @xBis7 for the review.