Remove obsolete --runbarelyexpensive parameter

Summary:
This is a relic from ancient times that is no longer in use.
See https://github.com/bitcoin/bitcoin/pull/8141.

Test Plan:

./test/functional/test_runner.py abc_p2p_compactblocks abc_p2p_fullblocktest

Reviewers: #bitcoin_abc, sdulfari

Reviewed By: #bitcoin_abc, sdulfari

Differential Revision: https://reviews.bitcoinabc.org/D11785