Reportstate volume size floc 976

Fixes FLOC-976
I'm not entirely sure what the motivation is for this, the commend reading "Change this to not create the Volume instance right away. Instead, try to find it by uuid/name in `check_for_volume`" was left by @exarkun and I was following that. By following the first part and not creating the volume instance immediately, there's no full object to compare on, so just the UUID is used. @itamarst may have some better idea of the motivation for this.