Remove dubbo monitor module

[CrazyHZM]

What is the purpose of the change

Brief changelog

Verifying this change

Checklist

• Make sure there is a GitHub_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GitHub issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Check if is necessary to patch to Dubbo 3 if you are work on Dubbo 2.7
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Add some description to dubbo-website project if you are requesting to add a feature.
• GitHub Actions works fine on your own branch.
• If this contribution is large, please follow the Software Donation Guide.

[sonarqubecloud]

Quality Gate passed

The SonarCloud Quality Gate passed, but some issues were introduced.

21 New issues
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (3f48269) 40.43% compared to head (b063de4) 35.99%.
Report is 69 commits behind head on 3.3.

Additional details and impacted files

@@            Coverage Diff             @@
##              3.3   #13456      +/-   ##
==========================================
- Coverage   40.43%   35.99%   -4.44%     
==========================================
  Files        1808     1757      -51     
  Lines       75893    73989    -1904     
  Branches    10642    10444     -198     
==========================================
- Hits        30687    26635    -4052     
- Misses      40886    43356    +2470     
+ Partials     4320     3998     -322     

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