use local chainman in peermanager_tests

Summary:
To remove usages of the global chainman in peermanager_tests, pass a reference to the active chainstate to two static functions who need it.

Depends on D11703

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D11737