move secrets from sops lookup plugin to sops vars plugin

This makes secret configuration and usage a good bit cleaner.

inventories/chaosknoten/host_vars/grafana.yaml

@@ -50,7 +50,7 @@ alloy_config: |
       url = "https://metrics.hamburg.ccc.de/api/v1/write"
       basic_auth {
         username = "chaos"
-        password = "{{ lookup('community.sops.sops', 'resources/chaosknoten/grafana/secrets.yaml', extract='['metrics_chaos"]') }}"
+        password = "{{ secret__metrics_chaos }}"
       }
     }
   }
@@ -59,7 +59,7 @@ alloy_config: |
       url = "https://loki.hamburg.ccc.de/loki/api/v1/push"
       basic_auth {
         username = "chaos"
-        password = "{{ lookup('community.sops.sops', 'resources/chaosknoten/grafana/secrets.yaml', extract='["loki_chaos"]') }}"
+        password = "{{ secret__loki_chaos }}"
       }
     }
   }