qa/tasks: Set default caps for 'osd' type in generate_caps()

qa/tasks: Set default caps for 'osd' type in generate_caps()

Assign the default caps for osds to be the same as what the AuthMonitor
sets for a new osd. See AuthMonitor::validate_osd_new() which sets the
following caps for a new osd:

 mon='allow profile osd'
 mgr='allow profile osd'
 osd=''allow *'

When an actual real world cluster is deployed, the above caps are applied.
Unless the user modifies the defaults, a cluster will operate with the
above caps. Therefore, it makes sense to use the defaults when testing
Ceph so that issues if any due to the default settings may be caught and
fixed.

Therefore, the caps for the 'osd' type is reset to the default in
generate_caps(). The caps for 'mgr' already reflects the system defaults.
The caps for 'mds' type is not changed in this commit and will be
investigated and changed if necessary later.

Signed-off-by: Sridhar Seshasayee <sseshasa@redhat.com>