On BSD, the storagenode-updater falls back to renaming the storagenode without
doing anything to restart the service.
Like the approach we have for linux, this change finds the process ID of the
storagenode using pgrep and sends an interrupt signal to the process.
Closes https://github.com/storj/storj/issues/5333
Change-Id: Icced90ea3e831528804784c2170a3b8b14952e8c
