feat: add leader election candidate namespace support#390

cc-datum wants to merge 1 commit intomaindatum-cloud/milo:mainfrom

389-leader-election-hardcodes-datum-system-namespace-causing-controllers-to-reconcile-across-namespacesdatum-cloud/milo:389-leader-election-hardcodes-datum-system-namespace-causing-controllers-to-reconcile-across-namespacesCopy head branch name to clipboard