Rename to '-excessiveblocksize' in abc-cmdline test

Summary:
Rename to '-excessiveblocksize' in abc-cmdline test.
It was failing as it should if the wrong option is
used.

The test is left disabled from the main suite pending
resolution of https://reviews.bitcoinabc.org/T30

Long-term, we should get better command line option
handling ported from Classic / BU - it would have
told us about the unrecognized option instead of
silently running with the wrong value.

Test Plan: qa/pull-tester/rpc-tests.py

Reviewers: #bitcoin_abc, deadalnix, sickpig, kyuupichan

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D178