What is the purpose of the change

issue#1689: Enhance the test coverage part-10 : dubbo-plugin module

Brief changelog

dubbo-plugin/dubbo-qos/src/test/java/org/apache/dubbo/qos/server/handler/LocalHostPermitHandlerTest.java
dubbo-plugin/dubbo-qos/src/test/java/org/apache/dubbo/qos/server/handler/QosProcessHandlerTest.java
dubbo-plugin/dubbo-qos/src/test/java/org/apache/dubbo/qos/server/handler/TelnetProcessHandlerTest.java

Verifying this change

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• 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 integration-test in test module.
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