ut: cpp ut support option zk_host:zk_port

Cpp ut defines zk port 6181 in code. If we want to modify it, we should rebuild the binary files. It's not good for testing.
We should support:
```
./build/bin/xxx_test --port 2181
```

The issue mentions C++ unit tests that hardcode a ZooKeeper port. Look for test binaries in ./build/bin/ that end with _test. The change involves adding command-line argument parsing (like --port) to these test executables, likely in their main() function. Check existing test code for similar argument handling. After modifying, rebuild the test binary and verify it accepts the new port option.

Written by the indexing model from the issue text.