Fix IPv4 address port parsing in NetUtils

[yin-bo-Final]

Fixes #16308

What is the purpose of the change?

This PR fixes NetUtils.matchIpExpression(String, String) so it can correctly parse normal IPv4 host:port addresses, such as 192.168.1.63:90.

Previously, the method only split the address when it ended with :, so a normal IPv4 address with port was treated as the full host string and could fail with UnknownHostException.

The fix parses the address only when it contains exactly one colon, avoiding impact on IPv6 addresses.

Checklist

• Make sure there is a GitHub_issue field for the change.
• 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. If the new feature or significant change is committed, please remember to add sample in dubbo samples project.
• Make sure gitHub actions can pass. Why the workflow is failing and how to fix it?

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 60.79%. Comparing base (ee9c190) to head (982f398).

Additional details and impacted files

@@             Coverage Diff              @@
##                3.3   #16309      +/-   ##
============================================
+ Coverage     60.77%   60.79%   +0.01%     
+ Complexity    11768       15   -11753     
============================================
  Files          1953     1953              
  Lines         89196    89196              
  Branches      13457    13458       +1     
============================================
+ Hits          54212    54223      +11     
+ Misses        29418    29405      -13     
- Partials       5566     5568       +2     

Flag	Coverage Δ
integration-tests-java21	32.11% <0.00%> (-0.01%)	⬇️
integration-tests-java8	32.24% <0.00%> (-0.01%)	⬇️
samples-tests-java21	32.13% <0.00%> (-0.06%)	⬇️
samples-tests-java8	29.83% <0.00%> (-0.03%)	⬇️
unit-tests-java11	59.01% <100.00%> (-0.03%)	⬇️
unit-tests-java17	58.51% <100.00%> (ø)
unit-tests-java21	58.53% <100.00%> (+0.04%)	⬆️
unit-tests-java25	58.44% <100.00%> (+0.03%)	⬆️
unit-tests-java8	59.04% <100.00%> (-0.01%)	⬇️

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[yin-bo-Final]

The failed Samples Test seems caused by Docker Hub timeout while pulling eclipse-temurin:21-jdk and mysql:5.7.40.