erasure-code: add thrash-erasure-code to suites/rados

Because it needs the thrasher to have min_in: 4 otherewise k=3,m=1 will
block.

http://tracker.ceph.com/issues/9648 Fixes: #9648

Signed-off-by: Loic Dachary <loic-201408@dachary.org>