Add disks_total to reported data
Fixes #32170 - Adding total_disk_size to host facets
This PR introduced new parameter to hosts facets. Parameter is a total
disk size that is included in Discovery plugin at own. However that
means that we have to maintain a two "facets like" codes at one time
(one at core, another one at discovery). This is attempt to unify
that and having only one code for that.