Drops swarm.otel.url (a loopback default an operator had to override on a
split host) in favor of swarm.otel.domain -- the same
gateway.localNames + nginx-vhost-through-the-gateway shape every other
swarm service (authelia, grafana, victoriametrics, ui) already uses. The
hive tier's exporter now reaches it as https://<domain> unconditionally,
resolved locally by dnsmasq on a co-located host and over the real network
otherwise, instead of a config knob nobody sets until they hit the silent
drop.
Costs CA trust on the hive tier: otel.nix wires
lib/hive-ca-trust.nix's trustBundle with hostUnit = true on the
opentelemetry-collector host unit, the same flag #3441/#3442 added for
swarm-controller and hive-c0re.
mara, #3125 comment 58363: "go c".
d2fb4bff79