[3.0] Add unit test for CountTelnetHandler

[icankeep]

What is the purpose of the change

#7842

Add unit test for CountTelnetHandler

• Make sure there is a GitHub_issue field for the change (usually before you start working on it). Trivial changes like typos do not require a GitHub issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
• Format the pull request title like [Dubbo-XXX] Fix UnknownException when host config not exist #XXX. Each commit in the pull request should have a meaningful subject line and body.
• Write a pull request description that is detailed enough to understand what the pull request does, how, and why.
• Write necessary unit-test to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Run mvn clean install -DskipTests=false & mvn clean test-compile failsafe:integration-test to make sure unit-test and integration-test pass.
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[codecov-commenter]

Codecov Report

Merging #7845 (e087a6c) into 3.0 (3a8f44e) will increase coverage by 0.21%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                3.0    #7845      +/-   ##
============================================
+ Coverage     58.22%   58.44%   +0.21%     
+ Complexity      404      403       -1     
============================================
  Files          1080     1080              
  Lines         43804    43804              
  Branches       6531     6531              
============================================
+ Hits          25505    25601      +96     
+ Misses        15480    15359     -121     
- Partials       2819     2844      +25     

Impacted Files	Coverage Δ	Complexity Δ
...ava/org/apache/dubbo/rpc/cluster/Configurator.java	4.00% <0.00%> (-32.00%)	0.00% <0.00%> (ø%)
...in/java/org/apache/dubbo/common/utils/JVMUtil.java	81.13% <0.00%> (-11.33%)	0.00% <0.00%> (ø%)
...e/dubbo/remoting/transport/netty/NettyChannel.java	52.27% <0.00%> (-7.96%)	19.00% <0.00%> (-2.00%)
.../apache/dubbo/remoting/transport/AbstractPeer.java	67.39% <0.00%> (-4.35%)	0.00% <0.00%> (ø%)
.../dubbo/registry/integration/RegistryDirectory.java	40.65% <0.00%> (-3.94%)	0.00% <0.00%> (ø%)
.../dubbo/remoting/transport/netty4/NettyChannel.java	64.35% <0.00%> (-1.99%)	0.00% <0.00%> (ø%)
...pache/dubbo/registry/support/AbstractRegistry.java	76.92% <0.00%> (-1.47%)	0.00% <0.00%> (ø%)
...rg/apache/dubbo/common/timer/HashedWheelTimer.java	63.44% <0.00%> (-1.04%)	0.00% <0.00%> (ø%)
...figcenter/file/FileSystemDynamicConfiguration.java	59.04% <0.00%> (-0.48%)	0.00% <0.00%> (ø%)
...n/java/org/apache/dubbo/common/utils/UrlUtils.java	60.92% <0.00%> (-0.28%)	0.00% <0.00%> (ø%)
... and 9 more

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[AlbumenJ]

Please also apply 1fddcb9 to this PR

[icankeep]

Please also apply 1fddcb9 to this PR

Done