Optimize AutoSwitchRoleBase#nextPort method

[mxsm]

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Remove the recursive call when binding port error occurs.

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[francisoliverlee]

可以补充下原方法的问题和优化思路，有单测的话更好

[mxsm]

可以补充下原方法的问题和优化思路，有单测的话更好

@francisoliverlee 这个就是测试里面的一个基本类， 我补充一下以优化思路