Split the Node_addOffline test into pri/sec
Split the Node_addOffline test into pri/sec

Currently, this (single) test checks whether we can add an instance as
primary and secondary to a given node. This won't work for instance
templates other than DRBD8, so we split it into:

- an add to primary test, which should work for all disk templates
- an add to secondary test, for which we set the disk template to DRBD
  explicitly

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Guido Trotter <f62ca4d5358bdaeef0e50e57f9f7e231de63727e@google.com>

yiannist/ganeti,leshchevds/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,ganeti/ganeti,leshchevds/ganeti,yiannist/ganeti,bitemyapp/ganeti,andir/ganeti,onponomarev/ganeti,andir/ganeti,leshchevds/ganeti,mbakke/ganeti,apyrgio/ganeti,apyrgio/snf-ganeti,dimara/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,mbakke/ganeti,dimara/ganeti,onponomarev/ganeti,ganeti/ganeti,apyrgio/ganeti,andir/ganeti,ganeti-github-testing/ganeti-test-1,grnet/snf-ganeti,yiannist/ganeti,mbakke/ganeti