This commit fixes to add prefixes to the blacklist. The blacklist was
moved to generate-tempest-plugins-list.py by the recent patch[0].
However, the blacklist was updated by the other patch[1] before that.
So, it should have been updated correctly when the conflict was
occurred.
[0] I707aba930037e86f5f94dac73da957f5afacf935
[1] Ieecb8989ff8959f1b2c0e5f2f6b8ea2c3ebbcaa9
Change-Id: I090dd235dd7911aa9bb0eb13d8e65b501dc206fe
6617b834ff