fix: Makes sure there always is an active issuer in Vault PKI #2360

Job	Run time
lint-report / lint-report	28s
grafana-dashboard-lint-report / lint-report	54s
Static analysis / static-analysis	42s
unit-tests-with-coverage / unit-tests	50s
build / build-kv-requirer	11m 28s
build / build-charm-under-test	15m 42s
integration-test / integration-test	35m 32s
publish-charm	0s
	1h 5m 36s

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