Add construction of domain in Helix participant logic

[zhangmeng916]

Issues

• [X ] My PR addresses the following Helix issues and references them in the PR description:

(#875 )

Description

• Here are some details about my PR, including screenshots of any UI changes:

Helix has a topology defined in cluster config, e.g., "TOPOLOGY": "/zone/host", and it will be used to construct the "domain" field in participant config, e.g. ""DOMAIN": "zone=0,host=host1". In Azure, Helix will provide a default topology value for the cluster, and the format is /faultDomain/hostName. In this pR, we add the construction function in Participant manager to construct the domain field based on this topology.

Tests

• The following is the result of the "mvn test" command on the appropriate module:

Commits

• [X ] My commits all reference appropriate Apache Helix GitHub issues in their subject lines. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters (not including Jira issue reference)
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Code Quality

• [X ] My diff has been formatted using helix-style.xml
  (helix-style-intellij.xml if IntelliJ IDE is used)

[junkaixue]

Do we need this? If we know the environment is Azure, then we can directly get the topology from AzureConstants instead of reading from ClusterConfig.

[zhangmeng916]

In this logic, we do not parse the cloud provider directly. That logic is in the processor. I was thinking that if we read from clusterConfig, it'll be generic, and independent of cloud provider. thoughts?

[zhangmeng916]

Discussed offline. We'll move the logic to cloud instance information processor and not to depend on cluster config.

[alirezazamani]

LGTM

[zhangmeng916]

This PR is ready to merge, approved by @dasahcc
Final commit message:
Add the construction of domain field in Azure cloud instance information processor. It will read the topology from AzureConstants, and construct the domain based on the format of the topology.