tests: test dashboard deployment with podman scenario

This commit adds a grafana-server section in order to test dashboard
deployment with podman.

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit 3c2fd337)

tests/functional/podman/hosts

@@ -26,5 +26,8 @@ rbd-mirror0
 [iscsigws]
 iscsi-gw0
 
+[grafana-server]
+mgr0
+
 #[all:vars]
 #ansible_python_interpreter=/usr/bin/python3
\ No newline at end of file