support multipe msggateway services in k8s deployments

[xuexihuang]

🔍 What type of PR is this?

👀 What this PR does / why we need it:

• My pull request adheres to the code style of this project
• My code requires changes to the documentation
• I have updated the documentation as required
• All the tests have passed

🅰 Which issue(s) this PR fixes:

Fixes #1564

📝 Special notes for your reviewer:

🎯 Describe how to verify it

📑 Additional documentation e.g., RFC, notion, Google docs, usage docs, etc.:

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[sweep-ai]

Apply Sweep Rules to your PR?

• Apply: All new business logic should have corresponding unit tests.
• Apply: Refactor large functions to be more modular.
• Apply: Add docstrings to all functions and file headers.

[codecov]

Codecov Report

Attention: 59 lines in your changes are missing coverage. Please review.

Comparison is base (01c3d47) 4.88% compared to head (b976b7c) 4.81%.

Files	Patch %	Lines
pkg/common/discoveryregister/discoveryregister.go	0.00%	59 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main   #1565      +/-   ##
========================================
- Coverage   4.88%   4.81%   -0.08%     
========================================
  Files         42      42              
  Lines       3787    3843      +56     
========================================
  Hits         185     185              
- Misses      3592    3648      +56     
  Partials      10      10              

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[xuexihuang]

I have read the CLA Document and I hereby sign the CLA