storagenode updater should remove older binaries after update

[shaupt131]

The updater after updating itself or the storagenode, only renames the old binary by appending .old.<version> to the binary name (in the case of the storagenode) or appending .old (in the case of the storagenode-updater).

This accumulates a lot of binary files on the storage location unless manually deleted:

The updater should delete the older binaries on restart.