fix metric query option for variable in DAL dashboard
This might have been carried over from the L1 node dashboards. But, the
dal node does not export such metric: octez_node
. As a consequence, my
DAL nodes do not show at all in my dashboard under "node instance"
Maybe it should export octez_node
anyway? In any case, I think that
there should be a metric unique to DAL nodes. That's how we recognize
DAL nodes amongst many types of nodes.