Bump the log crawling timeout after node restart in rpc_setban.py

Summary: The 5s timeout is occasionally too short for some of our slowest CI machines.

Test Plan:

./test/functional/test_runner.py rpc_setban

Reviewers: #bitcoin_abc, bytesofman

Reviewed By: #bitcoin_abc, bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D17830