daemonset.go was entirely dead: CreateDaemonSet, DeleteDaemonset,
AddRookVersionLabelToDaemonSet, and GetDaemonsets had no callers anywhere
in the repo (verified with grep, deadcode, and staticcheck). Rook does not
manage any DaemonSets via these helpers. Remove the file.
Signed-off-by: Joshua Hoblitt <josh@hoblitt.com>