Piece deletion service was using KnownReliable method from
overlaycache to get nodes addresses to send delete request.
KnownReliable was always hitting DB because this method was
not using cache. This change is using new DownloadSelectionCache
to avoid direct DB calls.
Change is not perfect because DownloadSelectionCache is not as
precise as KnownReliable method and can select few more nodes
to which we will send delete request but difference should be
small and we can improve it later.
Updates https://github.com/storj/storj/issues/4959
Change-Id: I4c3d91089a18ac35ebcb469a56536c33f76e44ea
d72f9525d4