fix: issues#3372

[sirius19]

https://github.com/alibaba/Sentinel/issues/3372

Describe what this PR does / why we need it

数据更新到nacos或其他地方时有延迟，导致修改完不会马上看到最新值

Does this pull request fix one issue?

Fixes #3372

Describe how you did it

保存时已先保存到内存，获取时优先从内存获取

Describe how to verify it

Special notes for reviews

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 45.93%. Comparing base (cd02b1d) to head (e0c13cf).

Additional details and impacted files

@@             Coverage Diff              @@
##                1.8    #3385      +/-   ##
============================================
+ Coverage     45.89%   45.93%   +0.03%     
- Complexity     2145     2148       +3     
============================================
  Files           431      431              
  Lines         12903    12903              
  Branches       1727     1727              
============================================
+ Hits           5922     5927       +5     
+ Misses         6279     6277       -2     
+ Partials        702      699       -3     

Components	Coverage Δ
sentinel-adapter	43.22% <ø> (ø)
sentinel-cluster	23.71% <ø> (ø)
sentinel-core	59.66% <ø> (+0.03%)	:arrow_up:
sentinel-extension	46.32% <ø> (+0.13%)	:arrow_up:
sentinel-logging	54.54% <ø> (ø)

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