[SCB-2643]fix instance isolation filter not work problem

[liubao68]

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[codecov-commenter]

Codecov Report

Merging #3310 (657c265) into 1.3.x (3ad1f9d) will increase coverage by 0.02%.
The diff coverage is 95.77%.

@@             Coverage Diff              @@
##              1.3.x    #3310      +/-   ##
============================================
+ Coverage     83.00%   83.02%   +0.02%     
  Complexity      746      746              
============================================
  Files          1233     1233              
  Lines         33084    33046      -38     
  Branches       3001     2995       -6     
============================================
- Hits          27461    27437      -24     
+ Misses         4438     4432       -6     
+ Partials       1185     1177       -8     

Impacted Files	Coverage Δ
...rg/apache/servicecomb/loadbalance/BeansHolder.java	100.00% <ø> (ø)
...e/servicecomb/loadbalance/ServerListFilterExt.java	66.66% <0.00%> (+33.33%)	⬆️
...ervicecomb/loadbalance/ServiceCombServerStats.java	88.37% <ø> (ø)
...cecomb/loadbalance/event/IsolationServerEvent.java	58.33% <ø> (ø)
...servicecomb/loadbalance/SessionStickinessRule.java	83.63% <50.00%> (ø)
...oadbalance/filterext/ZoneAwareDiscoveryFilter.java	96.66% <96.66%> (ø)
...g/apache/servicecomb/loadbalance/LoadBalancer.java	100.00% <100.00%> (+15.15%)	⬆️
.../apache/servicecomb/loadbalance/RandomRuleExt.java	60.00% <100.00%> (-6.67%)	⬇️
...che/servicecomb/loadbalance/RoundRobinRuleExt.java	100.00% <100.00%> (ø)
...che/servicecomb/loadbalance/ServiceCombServer.java	96.55% <100.00%> (+0.12%)	⬆️
... and 13 more

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