What is the purpose of the change

Make NetUtilsTest#testGetIpByHost() run successfully.

see #7552

Brief changelog

update NetUtilsTest#testGetIpByHost() test case

Reason

In some companies, there are short domains to simplify the full domain. So, the OPS team will set some rules to convert the short domain to IP address. Sometimes, the short domains is a string without separating with dots.

There are some examples in my company below:

• run ping dubbo
  

• run ping assdfasdfasdfasd
  

• run ping dubbo.local
  

Solution

Update the domain and make sure the domain contains dot.

Also, we can see the domain dubbo has been updated to dubbo.local in the branch of 3.0

So, we'd better update the domain from dubbo to dubbo.local

Verifying this change

• 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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