[avalanche] Cleanup the proof voting test
[avalanche] Cleanup the proof voting test

Summary:
 - Remove dangling log
 - Remove duplicated test case
 - Remove duplicated peer
 - Remove the wait_for_disconnect and whitelist the locahost.
   This leads to a minor duration gain which will turn huge in the next
   diff.

Test Plan:
  ./test/functional/test_runner.py abc_p2p_avalanche_proof_voting

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D12176

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