fix(storagedirective): fix storage directive validator #935

Job	Run time
Build	1m 41s
Integration (1.6.*, 5.19/stable, lxd, 5.19, 2.9)	40m 30s
Integration (1.6.*, 5.19/stable, lxd, 5.19, 3)	37m 55s
Integration (1.6.*, 5.19/stable, microk8s, 1.28, 2.9)	13m 44s
Integration (1.6.*, 5.19/stable, microk8s, 1.28-strict, 3)	12m 28s
Integration (1.7.*, 5.19/stable, lxd, 5.19, 2.9)	38m 14s
Integration (1.7.*, 5.19/stable, lxd, 5.19, 3)	44m 56s
Integration (1.7.*, 5.19/stable, microk8s, 1.28, 2.9)	10m 29s
Integration (1.7.*, 5.19/stable, microk8s, 1.28-strict, 3)	11m 43s
Integration (1.8.*, 5.19/stable, lxd, 5.19, 2.9)	38m 27s
Integration (1.8.*, 5.19/stable, lxd, 5.19, 3)	44m 59s
Integration (1.8.*, 5.19/stable, microk8s, 1.28, 2.9)	12m 8s
Integration (1.8.*, 5.19/stable, microk8s, 1.28-strict, 3)	11m 11s
	5h 18m 25s

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