optimization of duplicate code

[CrazyHZM]

What is the purpose of the change

Optimize the duplicate code of FailbackRegistry.java.

Brief changelog

XXXXX

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #2832 into 2.6.x will increase coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##              2.6.x    #2832      +/-   ##
============================================
+ Coverage     47.42%   47.44%   +0.01%     
+ Complexity     4294     4292       -2     
============================================
  Files           552      552              
  Lines         24381    24381              
  Branches       4314     4314              
============================================
+ Hits          11563    11567       +4     
+ Misses        11035    11029       -6     
- Partials       1783     1785       +2

Impacted Files	Coverage Δ	Complexity Δ
...om/alibaba/dubbo/rpc/filter/ActiveLimitFilter.java	83.33% <0%> (-5.56%)	6% <0%> (-1%)
...rpc/protocol/dubbo/telnet/InvokeTelnetHandler.java	54.21% <0%> (-3.62%)	13% <0%> (-2%)
...baba/dubbo/remoting/transport/mina/MinaClient.java	57.81% <0%> (-1.57%)	8% <0%> (-1%)
...onfig/spring/extension/SpringExtensionFactory.java	83.78% <0%> (+8.1%)	9% <0%> (ø)	⬇️
...a/dubbo/remoting/transport/netty/NettyChannel.java	66.25% <0%> (+8.75%)	21% <0%> (+2%)	⬆️

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[carryxyh]

The code for this part has been completely reconfigured in another PR.
If we don't accept that pr, I will handle this pr. Let it stay open first.

[CrazyHZM]

first
Hard work,thanks.

[carryxyh]

noting changed ?

[CrazyHZM]

Sorry, I accidentally mishandled.