Remove suspicious hosts list from makeseeds

Summary:
Backport of core#24862 and skipping core#17823

The list is outdated and unmaintained. Additional rationale can be found in the original pr.

Test Plan: Run makeseeds according to readme.

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D12143