Reorganize the dependency in dubbo-demo

[wcy666103]

What is the purpose of the change?

Currently, the dependencies in dubbo-demo are somewhat redundant—for example, even though Zookeeper is being used, the Nacos dependency is still included. The configuration files also contain unnecessary entries, such as qos = false. Additionally, there are some improper usage practices. We need to reorganize the project by keeping only the minimal required set, and improve the README.md documentation to lower the barrier for users to use and learn from the demo.

ref #15380

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 60.75%. Comparing base (d6b11cf) to head (c308fe0).

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #15384      +/-   ##
============================================
+ Coverage     60.73%   60.75%   +0.02%     
+ Complexity    10920    10919       -1     
============================================
  Files          1886     1886              
  Lines         86162    86162              
  Branches      12913    12913              
============================================
+ Hits          52328    52346      +18     
+ Misses        28374    28345      -29     
- Partials       5460     5471      +11     

Flag	Coverage Δ
integration-tests	33.15% <ø> (+0.03%)	⬆️
samples-tests	29.33% <ø> (-0.03%)	⬇️
unit-tests	58.90% <ø> (+0.06%)	⬆️

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