cmdlib._CreateDisks fix a broken result.Raise
cmdlib._CreateDisks fix a broken result.Raise

The format string has the ": %s" at the end, but no argument is passed,
which of course raises a TypeError. Removing ": %s" as it's added by
the RpcResult Raise() method anyway.

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

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