Migration bugfix & optimization

[mytang0]

What is the purpose of the change

1. Fix volatile problem
2. Thread pool leak fix
3. Code optimization

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]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

84.0% Coverage
0.0% Duplication

[codecov-commenter]

Codecov Report

Merging #11629 (04fe387) into 3.2 (10e7162) will decrease coverage by 0.14%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                3.2   #11629      +/-   ##
============================================
- Coverage     69.73%   69.59%   -0.14%     
+ Complexity      339        2     -337     
============================================
  Files          1573     1382     -191     
  Lines         84263    59982   -24281     
  Branches      15298     8915    -6383     
============================================
- Hits          58758    41747   -17011     
+ Misses        20584    14092    -6492     
+ Partials       4921     4143     -778     

Impacted Files	Coverage Δ
...t/migration/DefaultMigrationAddressComparator.java
...bo/registry/client/migration/MigrationInvoker.java
...egistry/client/migration/MigrationRuleHandler.java
...gistry/client/migration/MigrationRuleListener.java
...moting/transport/netty4/Netty4BatchWriteQueue.java
...ache/dubbo/cache/support/expiring/ExpiringMap.java
...gistrycenter/initializer/ZookeeperInitializer.java
...enter/support/nacos/NacosConfigServiceWrapper.java
...ache/dubbo/rpc/protocol/dubbo/DubboCountCodec.java
...adata/store/zookeeper/ZookeeperMetadataReport.java
... and 2945 more

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[AlbumenJ]

LGTM