Parallelize LU{A,Dea}ctivateInstanceDisks
Parallelize LU{A,Dea}ctivateInstanceDisks

Now that they are not used in other opcodes by chaining,
this can easily be done.

Reviewed-by: iustinp


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