Add snapshot retention folder fix #253

Job	Run time
build / Build	6m 23s
Integration Tests (certrotation)	1m 39s
Integration Tests (etcdrestore)	2m 4s
Integration Tests (localstorage)	1m 50s
Integration Tests (startup)	8m 18s
Integration Tests (custometcdargs)	39s
Integration Tests (etcdsnapshot)	7m 43s
Integration Tests (kubeflags)	7m 2s
Integration Tests (longhorn)	2m 58s
Integration Tests (secretsencryption)	2m 12s
Integration Tests (flannelnone)	1m 34s
	42m 22s

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