Add more detach/attach sequence tests
Add more detach/attach sequence tests

Test detach/attach sequences with an instance that becomes diskless
after detaching its disk and also test detach/attach with drbd disks.

Signed-off-by: Lisa Velden <f95ae155456787aef400a49db463a62bbef84ead@google.com>
Reviewed-by: Oleg Ponomarev <c100474c6090841e9d55cde74d38d81efd269b8d@google.com>

mbakke/ganeti,leshchevds/ganeti,andir/ganeti,leshchevds/ganeti,andir/ganeti,onponomarev/ganeti,andir/ganeti,yiannist/ganeti,ganeti/ganeti,yiannist/ganeti,yiannist/ganeti,mbakke/ganeti,ganeti/ganeti,leshchevds/ganeti,mbakke/ganeti,ganeti/ganeti,onponomarev/ganeti