Remove dubbo-test in dubbo-metrics,dubbo-registry,dubbo-serialization

[Stellar1999]

What is the purpose of the change?

This is part of the process of removing the dubbo-test module.

Checklist

• Make sure there is a GitHub_issue field for the change.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.78%. Comparing base (3e5216f) to head (60a2ce8).

Additional details and impacted files

@@            Coverage Diff            @@
##                3.3   #15218   +/-   ##
=========================================
  Coverage     60.78%   60.78%           
- Complexity    10890    10896    +6     
=========================================
  Files          1885     1885           
  Lines         86072    86072           
  Branches      12892    12892           
=========================================
+ Hits          52319    52321    +2     
- Misses        28306    28309    +3     
+ Partials       5447     5442    -5     

Flag	Coverage Δ
integration-tests	33.23% <ø> (+0.14%)	⬆️
samples-tests	29.19% <ø> (+<0.01%)	⬆️
unit-tests	58.89% <ø> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Stellar1999]

@CrazyHZM PTAL