Seeder: do not exclude nodes that use a non-default port

Summary: Historically Bitcoin (ABC) had a strong preference for using the default port, but as of D12344 this is no longer the case. So the seeder should stop considering nodes using non-default ports unreliable.

Test Plan: ninja check-seeder

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D16489