Update AbstractConfig.java

[dadadadudu]

配置中心的覆盖注释错误，APP优先于全局配置

What is the purpose of the change

注释与实现不符

Brief changelog

XXXXX

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #3737 into master will increase coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #3737      +/-   ##
============================================
+ Coverage     63.58%   63.61%   +0.02%     
  Complexity       71       71              
============================================
  Files           703      703              
  Lines         31000    31000              
  Branches       5022     5022              
============================================
+ Hits          19712    19721       +9     
+ Misses         9018     9012       -6     
+ Partials       2270     2267       -3

Impacted Files	Coverage Δ	Complexity Δ
...n/java/org/apache/dubbo/config/AbstractConfig.java	79.57% <ø> (ø)	0 <0> (ø)	⬇️
...pache/dubbo/registry/support/AbstractRegistry.java	79.52% <0%> (-1.19%)	0% <0%> (ø)
...dubbo/remoting/exchange/support/DefaultFuture.java	73.46% <0%> (+0.68%)	0% <0%> (ø)	⬇️
...exchange/support/header/HeaderExchangeHandler.java	62.79% <0%> (+2.32%)	0% <0%> (ø)	⬇️
.../org/apache/dubbo/remoting/ExecutionException.java	21.05% <0%> (+5.26%)	0% <0%> (ø)	⬇️
...ng/exchange/support/header/HeartbeatTimerTask.java	78.94% <0%> (+5.26%)	0% <0%> (ø)	⬇️
...ng/transport/dispatcher/all/AllChannelHandler.java	57.14% <0%> (+5.71%)	0% <0%> (ø)	⬇️
.../remoting/transport/netty4/NettyServerHandler.java	71.42% <0%> (+9.52%)	0% <0%> (ø)	⬇️

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[ralf0131]

LGTM, thanks for the pull request~