[tests] Remove unused and duplicate imports
Summary:
[tests] Remove unused and duplicate imports
Backport of Core PR10047
https://github.com/bitcoin/bitcoin/pull/10047/
Commit 1/2
Test Plan:
test_runner.py
Reviewers: jasonbcox, Fabien, deadalnix, markblundeberg, O1 Bitcoin ABC, #bitcoin_abc
Reviewed By: Fabien, O1 Bitcoin ABC, #bitcoin_abc
Differential Revision: https://reviews.bitcoinabc.org/D3023