Add log in ZkclientZookeeperClient.java

[CrazyHZM]

What is the purpose of the change

add log in ZkclientZookeeperClient.java

Brief changelog

XXXXX

Verifying this change

XXXXX

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[codecov-io]

Codecov Report

Merging #3109 into master will decrease coverage by 0.04%.
The diff coverage is 11.11%.

@@             Coverage Diff              @@
##             master    #3109      +/-   ##
============================================
- Coverage     63.63%   63.59%   -0.05%     
  Complexity       75       75              
============================================
  Files           653      653              
  Lines         28210    28219       +9     
  Branches       4794     4794              
============================================
- Hits          17951    17945       -6     
- Misses         7999     8009      +10     
- Partials       2260     2265       +5

Impacted Files	Coverage Δ	Complexity Δ
...ng/zookeeper/zkclient/ZkclientZookeeperClient.java	55% <11.11%> (-7.75%)	0 <0> (ø)
...ache/dubbo/remoting/p2p/support/AbstractGroup.java	45.45% <0%> (-11.37%)	0% <0%> (ø)
.../remoting/transport/netty4/NettyClientHandler.java	75% <0%> (-11.12%)	0% <0%> (ø)
.../apache/dubbo/remoting/transport/AbstractPeer.java	63.04% <0%> (-4.35%)	0% <0%> (ø)
...he/dubbo/remoting/transport/netty/NettyServer.java	67.85% <0%> (-3.58%)	0% <0%> (ø)
...he/dubbo/registry/multicast/MulticastRegistry.java	63.79% <0%> (-1.73%)	0% <0%> (ø)
...rpc/protocol/dubbo/telnet/InvokeTelnetHandler.java	72.5% <0%> (-1.67%)	0% <0%> (ø)
...pache/dubbo/remoting/transport/AbstractServer.java	47.91% <0%> (-1.05%)	0% <0%> (ø)
.../java/org/apache/dubbo/config/ReferenceConfig.java	57.57% <0%> (-0.38%)	0% <0%> (ø)
...pache/dubbo/registry/support/AbstractRegistry.java	82.33% <0%> (+0.37%)	0% <0%> (ø)	⬇️
... and 2 more

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