ceph-qa-suite: updating Hadoop tests

Changes to the teuthology YAML parsing
necessitates a small tweak to the Hadoop
and libceph-fs YAML files.

Signed-off-by: Joe Buck <jbbuck@gmail.com>
rbd: add read flags test with each cache mode

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>