[SCB-2811] support global route rule for gray (#3948)

[chengyouling]

No description provided.

[codecov-commenter]

Codecov Report

Merging #3949 (791e55a) into 2.8.x (8d1d911) will increase coverage by 0.01%.
The diff coverage is 87.50%.

❗ Current head 791e55a differs from pull request most recent head 9e1bc73. Consider uploading reports for the commit 9e1bc73 to get more accurate results

@@             Coverage Diff              @@
##              2.8.x    #3949      +/-   ##
============================================
+ Coverage     74.17%   74.18%   +0.01%     
  Complexity      703      703              
============================================
  Files          1597     1597              
  Lines         40164    40170       +6     
  Branches       3663     3667       +4     
============================================
+ Hits          29793    29802       +9     
+ Misses         8888     8886       -2     
+ Partials       1483     1482       -1     

Files Changed	Coverage Δ
...ache/servicecomb/router/cache/RouterRuleCache.java	65.30% <87.50%> (+7.16%)	⬆️

... and 2 files with indirect coverage changes

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