Switch to using kubelet config file for all supported flags #9014

Job	Run time
build / Build	6m 56s
Integration Tests (certrotation)	1m 20s
Integration Tests (cacertrotation)	1m 33s
Integration Tests (etcdrestore)	1m 28s
Integration Tests (localstorage)	1m 21s
Integration Tests (startup)	6m 35s
Integration Tests (custometcdargs)	39s
Integration Tests (etcdsnapshot)	7m 14s
Integration Tests (kubeflags)	6m 25s
Integration Tests (longhorn)	2m 14s
Integration Tests (secretsencryption)	2m 24s
Integration Tests (flannelnone)	1m 2s
	39m 11s

Provide feedback