[Dubbo-5855] ReferenceConfig(null) is not DESTROYED when FINALIZE

[lkj41110]

What is the purpose of the change

fix #5855

Verifying this change

delete finalizerGuardian

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[codecov-io]

Codecov Report

Merging #5863 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##             master    #5863      +/-   ##
============================================
- Coverage     61.24%   61.21%   -0.03%     
+ Complexity      499      497       -2     
============================================
  Files           981      981              
  Lines         39142    39141       -1     
  Branches       5643     5644       +1     
============================================
- Hits          23973    23961      -12     
- Misses        12542    12550       +8     
- Partials       2627     2630       +3     

Impacted Files	Coverage Δ	Complexity Δ
.../java/org/apache/dubbo/config/ReferenceConfig.java	68.20% <ø> (-0.80%)	0.00 <0.00> (ø)
...e/dubbo/remoting/transport/netty/NettyChannel.java	55.68% <0.00%> (-4.55%)	20.00% <0.00%> (-1.00%)
.../remoting/transport/netty4/NettyClientHandler.java	57.62% <0.00%> (-1.70%)	0.00% <0.00%> (ø%)
...pache/dubbo/registry/support/AbstractRegistry.java	78.06% <0.00%> (-1.49%)	0.00% <0.00%> (ø%)
...che/dubbo/remoting/transport/mina/MinaChannel.java	50.00% <0.00%> (-1.32%)	16.00% <0.00%> (-1.00%)
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	81.75% <0.00%> (-0.96%)	0.00% <0.00%> (ø%)
...g/apache/dubbo/registry/consul/ConsulRegistry.java	62.73% <0.00%> (+0.62%)	30.00% <0.00%> (ø%)

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