transport: send back only the requested columns
transport: send back only the requested columns

result_set may contain more columns than user requested (for instance if
some of them were needed to properly sort output). The additional columns
are always the last ones and are not included in metadata::column_count().

Signed-off-by: Paweł Dziepak <e29bb3265626c60caf76d587cabdfcd8b379ef80@cloudius-systems.com>

avikivity/scylla,stamhe/scylla,asias/scylla,justintung/scylla,capturePointer/scylla,stamhe/scylla,kangkot/scylla,aruanruan/scylla,eklitzke/scylla,dwdm/scylla,gwicke/scylla,victorbriz/scylla,phonkee/scylla,kangkot/scylla,phonkee/scylla,capturePointer/scylla,victorbriz/scylla,tempbottle/scylla,senseb/scylla,duarten/scylla,gwicke/scylla,scylladb/scylla,aruanruan/scylla,raphaelsc/scylla,avikivity/scylla,asias/scylla,eklitzke/scylla,victorbriz/scylla,justintung/scylla,kjniemi/scylla,raphaelsc/scylla,glommer/scylla,rentongzhang/scylla,guiquanz/scylla,justintung/scylla,duarten/scylla,shaunstanislaus/scylla,acbellini/scylla,rentongzhang/scylla,wildinto/scylla,kjniemi/scylla,kangkot/scylla,rluta/scylla,aruanruan/scylla,tempbottle/scylla,tempbottle/scylla,glommer/scylla,scylladb/scylla,respu/scylla,eklitzke/scylla,bowlofstew/scylla,scylladb/scylla,glommer/scylla,wildinto/scylla,bowlofstew/scylla,rluta/scylla,duarten/scylla,raphaelsc/scylla,gwicke/scylla,guiquanz/scylla,senseb/scylla,stamhe/scylla,respu/scylla,scylladb/scylla,phonkee/scylla,dwdm/scylla,shaunstanislaus/scylla,avikivity/scylla,linearregression/scylla,kjniemi/scylla,rentongzhang/scylla,asias/scylla,guiquanz/scylla,acbellini/scylla,shaunstanislaus/scylla,rluta/scylla,linearregression/scylla,dwdm/scylla,capturePointer/scylla,bowlofstew/scylla,wildinto/scylla,respu/scylla,linearregression/scylla,acbellini/scylla,senseb/scylla