Fix thanos-query.opstracegcp.com endpoint and remove inexistant db-integration endpoints in Thanos Query config

https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/16949#note_1205308154

Looks like thanos-query does set the Host header when not using DNS-SD, and this endpoint won't work without it.

The db-integration endpoints don't resolve to anything and cause lots of warnings so let's remove them.

See also gitlab-helmfiles!1453 (merged)