DPE-1965 - chore: use keytool snap app #712

Job	Run time
Lint	42s
Unit tests	1m 15s
Build charms / Get workflow version / Get workflow version	3s
Build charms / Collect charms	18s
Build charms / Build kafka charm \| 22.04	2m 21s
Build charms / Build application charm \| 22.04	2m 7s
integration-charm	19m 51s
integration-provider	34m 36s
integration-scaling	13m 15s
integration-password-rotation	12m 38s
integration-tls	20m 39s
integration-upgrade	27m 15s
	2h 15m 0s

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