alertmanager: adapt storage mounted to prometheus changes
alertmanager: adapt storage mounted to prometheus changes

gianrubio/prometheus-operator,mmerrill3/prometheus-operator,jescarri/prometheus-operator,eedugon/prometheus-operator,brancz/prometheus-operator,gianrubio/prometheus-operator,jescarri/prometheus-operator,brancz/prometheus-operator,mmerrill3/prometheus-operator,coreos/prometheus-operator,mmerrill3/prometheus-operator,brancz/prometheus-operator,gianrubio/prometheus-operator,eedugon/prometheus-operator,coreos/prometheus-operator