A trivial optimisation in Loader.mergeData
A trivial optimisation in Loader.mergeData

During loading, we can eliminate some intermediate data
structures. This only matters for big clusters, and even there it's
less than 1% less memory allocated, but still, it's a no-brainer.

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: René Nussbaumer <bc755ac45a0e799d1d490cba76febc56d80cc5fc@google.com>

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