add TelnetHandlerAdapterTest to branch 3.0

[dgzpg]

What is the purpose of the change

add TelnetHandlerAdapterTest to branch 3.0
see more detail from #8257

Brief changelog

Verifying this change

Checklist

• 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.
• 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.
• Check if is necessary to patch to Dubbo 3 if you are work on Dubbo 2.7
• 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.
• Add some description to dubbo-website project if you are requesting to add a feature.
• GitHub Actions works fine on your own branch.
• If this contribution is large, please follow the Software Donation Guide.

[horizonzy]

LGTM.

[codecov-commenter]

Codecov Report

Merging #8267 (f378144) into 3.0 (e321324) will increase coverage by 0.04%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##                3.0    #8267      +/-   ##
============================================
+ Coverage     64.06%   64.10%   +0.04%     
  Complexity      313      313              
============================================
  Files          1073     1073              
  Lines         45229    45271      +42     
  Branches       6816     6813       -3     
============================================
+ Hits          28974    29022      +48     
+ Misses        13044    13040       -4     
+ Partials       3211     3209       -2     

Impacted Files	Coverage Δ
...org/apache/dubbo/common/serialize/ObjectInput.java	33.33% <0.00%> (-33.34%)	⬇️
...rg/apache/dubbo/common/serialize/ObjectOutput.java	66.66% <0.00%> (-33.34%)	⬇️
...apache/dubbo/rpc/protocol/dubbo/FutureAdapter.java	36.00% <0.00%> (-8.00%)	⬇️
.../dubbo/rpc/protocol/dubbo/DecodeableRpcResult.java	52.00% <0.00%> (-8.00%)	⬇️
...ng/transport/dispatcher/all/AllChannelHandler.java	89.65% <0.00%> (-6.90%)	⬇️
...vent/listener/ServiceInstancesChangedListener.java	55.85% <0.00%> (-6.39%)	⬇️
...rg/apache/dubbo/rpc/protocol/dubbo/DubboCodec.java	63.39% <0.00%> (-5.36%)	⬇️
.../dubbo/remoting/transport/netty4/NettyChannel.java	64.35% <0.00%> (-1.99%)	⬇️
...pache/dubbo/registry/support/AbstractRegistry.java	78.10% <0.00%> (-1.83%)	⬇️
...he/dubbo/registry/multicast/MulticastRegistry.java	67.59% <0.00%> (-0.93%)	⬇️
... and 15 more

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[BurningCN]

LGTM