fix staking approval e2e test #319

Job	Run time
typescript-formatting	53s
build (fast, --features fast-runtime)	13m 59s
build (release)	13m 28s
typescript-e2e-zombienet_subnets	2m 18s
typescript-e2e-dev	57s
typescript-e2e-zombienet_shield	18m 18s
typescript-e2e-zombienet_staking	12m 34s
typescript-e2e-zombienet_coldkey_swap	6m 13s
	1h 8m 40s

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