optimize: optimize namingserver

[ggbocoder]

• I have registered the PR changes.

Ⅰ. Describe what this PR did

fix some problems in namingserver

Ⅱ. Does this pull request fix one issue?

Ⅲ. Why don't you add test cases (unit test/integration test)?

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Attention: Patch coverage is 81.81818% with 8 lines in your changes missing coverage. Please review.

Project coverage is 50.51%. Comparing base (1171548) to head (128bda9).
Report is 1 commits behind head on 2.x.

Files	Patch %	Lines
...ache/seata/namingserver/manager/NamingManager.java	80.00%	0 Missing and 2 partials ⚠️
...ache/seata/server/controller/NamingController.java	0.00%	2 Missing ⚠️
...e/seata/common/metadata/namingserver/Instance.java	50.00%	1 Missing ⚠️
...ta/namingserver/manager/ClusterWatcherManager.java	50.00%	1 Missing ⚠️
...ge/redis/store/RedisVGroupMappingStoreManager.java	50.00%	0 Missing and 1 partial ⚠️
.../seata/server/store/VGroupMappingStoreManager.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##                2.x    #6755      +/-   ##
============================================
- Coverage     50.52%   50.51%   -0.02%     
- Complexity     5924     5926       +2     
============================================
  Files          1061     1061              
  Lines         37082    37088       +6     
  Branches       4401     4398       -3     
============================================
- Hits          18736    18735       -1     
- Misses        16447    16454       +7     
  Partials       1899     1899              

Files	Coverage Δ
...ava/org/apache/seata/common/ConfigurationKeys.java	0.00% <ø> (ø)
...eata/namingserver/controller/NamingController.java	38.88% <ø> (+1.05%)	⬆️
...he/seata/namingserver/entity/pojo/ClusterData.java	63.15% <100.00%> (-0.64%)	⬇️
...org/apache/seata/server/session/SessionHolder.java	52.59% <100.00%> (ø)
...rage/file/store/FileVGroupMappingStoreManager.java	69.81% <100.00%> (-6.79%)	⬇️
...e/seata/common/metadata/namingserver/Instance.java	42.64% <50.00%> (+0.85%)	⬆️
...ta/namingserver/manager/ClusterWatcherManager.java	30.43% <50.00%> (+2.17%)	⬆️
...ge/redis/store/RedisVGroupMappingStoreManager.java	75.86% <50.00%> (-2.71%)	⬇️
.../seata/server/store/VGroupMappingStoreManager.java	72.72% <50.00%> (-7.28%)	⬇️
...ache/seata/namingserver/manager/NamingManager.java	59.01% <80.00%> (-0.13%)	⬇️
... and 1 more

... and 1 file with indirect coverage changes

[funky-eyes]

LGTM