[DUBBO-5237] fix NetUtils#isPreferIPV6Address() always return false

[wangkezun]

What is the purpose of the change

Fix #5237

Brief changelog

fix NetUtils#isPreferIPV6Address()

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #5238 into master will increase coverage by 0.51%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master    #5238      +/-   ##
============================================
+ Coverage     63.57%   64.08%   +0.51%     
+ Complexity      463      461       -2     
============================================
  Files           791      770      -21     
  Lines         35225    33396    -1829     
  Branches       5503     5261     -242     
============================================
- Hits          22394    21402     -992     
+ Misses        10302     9565     -737     
+ Partials       2529     2429     -100

Impacted Files	Coverage Δ	Complexity Δ
...n/java/org/apache/dubbo/common/utils/NetUtils.java	67.85% <0%> (+0.79%)	0 <0> (ø)	⬇️
.../apache/dubbo/qos/protocol/QosProtocolWrapper.java	70.73% <0%> (-12.2%)	0% <0%> (ø)
...che/dubbo/remoting/transport/mina/MinaChannel.java	43.42% <0%> (-10.53%)	16% <0%> (-1%)
.../remoting/transport/netty4/NettyServerHandler.java	65.21% <0%> (-8.7%)	0% <0%> (ø)
.../apache/dubbo/rpc/protocol/AsyncToSyncInvoker.java	79.16% <0%> (-8.34%)	0% <0%> (ø)
...ng/transport/dispatcher/all/AllChannelHandler.java	51.42% <0%> (-5.72%)	0% <0%> (ø)
...mmon/threadpool/support/AbortPolicyWithReport.java	83.78% <0%> (-5.41%)	0% <0%> (ø)
...ng/exchange/support/header/HeartbeatTimerTask.java	73.68% <0%> (-5.27%)	0% <0%> (ø)
.../org/apache/dubbo/remoting/ExecutionException.java	15.78% <0%> (-5.27%)	0% <0%> (ø)
...he/dubbo/remoting/transport/netty/NettyServer.java	70.17% <0%> (-3.51%)	8% <0%> (-1%)
... and 30 more

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[htynkn]

I believe changes are introduced by this PR: #3953
@lexburner @beiwei30 Could you have a look and confirm if this is a bug?

[lexburner]

I believe changes are introduced by this PR: #3953
@lexburner @beiwei30 Could you have a look and confirm if this is a bug?

You are right. The PR: #3953 remove the reachable check in the method isPreferIPV6Address.Such changes will cause always return false.
@wangkezun Thanks for your pr.