fix multiple subscribe error

[ZLBer]

Bugfix:

Using method computeIfAbsent avoid creating multiple informers and some Listeners failure due to multiple subscribe.

[codecov]

Codecov Report

Merging #1179 (006d38c) into master (1e7cd58) will increase coverage by 0.06%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master    #1179      +/-   ##
============================================
+ Coverage     71.12%   71.19%   +0.06%     
- Complexity      825      826       +1     
============================================
  Files           407      407              
  Lines         17199    17198       -1     
  Branches       2681     2680       -1     
============================================
+ Hits          12233    12244      +11     
+ Misses         3586     3579       -7     
+ Partials       1380     1375       -5     

Impacted Files	Coverage Δ
...lipay/sofa/rpc/registry/consul/ConsulRegistry.java	47.51% <100.00%> (+0.26%)	⬆️
...om/alipay/sofa/rpc/server/triple/TripleServer.java	73.88% <0.00%> (-1.12%)	⬇️
...va/com/alipay/sofa/rpc/client/AbstractCluster.java	70.68% <0.00%> (+0.26%)	⬆️
...ipay/sofa/rpc/tracer/sofatracer/RpcSofaTracer.java	91.06% <0.00%> (+0.74%)	⬆️
...lipay/sofa/rpc/message/AbstractResponseFuture.java	57.89% <0.00%> (+1.75%)	⬆️
...ipay/sofa/rpc/server/bolt/BoltServerProcessor.java	69.59% <0.00%> (+4.72%)	⬆️

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[OrezzerO]

LGTM

[EvenLjj]

LGTM