VictoriaLogs' own metrics were scraped over loopback, declared only on
the host running the store, so a collector on any other host had no job
for it. Its target is now declared on every host as
`https://<swarm.victorialogs.domain>/metrics`, next to forgejo's and
authelia's, and the store's vhost serves `= /metrics` behind a bare
`auth_request` to authelia. The rules derived from
`publishedScrapeTargets` admit the collector's client there and deny every
other subject. The loopback entry is gone, so a single host still scrapes
the store once, now by name.
On that vhost `/metrics` was reachable through the `/` location by any
authelia session. The exact-match location now takes it, so a session
gets a `deny` on `/metrics` and nothing else on the name changes.
Part of #5205
5fe04da559