Merge #10278: [test] Add Unit Test for GetListenPort

Summary:
1b14449 [test] Add Unit Test for GetListenPort (Jimmy Song)

Tree-SHA512: aea5f60fb3699680cc5acac9d9c8d8712634db9d629bbfa1815a29e5cf46c22f783886c608664baaa91b3282c52ce8069c358850cf4f90acf731a9e6c1701caa

Backport Core PR10278
https://github.com/bitcoin/bitcoin/pull/10278/files

Test Plan: make check

Reviewers: #bitcoin_abc, deadalnix, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D3176