update mock collector config (#1181)

Author: aphralG

test/mock/collector/nginx-agent.conf

@@ -49,7 +49,8 @@ collector:
         network: {}
         filesystem: {}
     otlp:
-      - server:
+      "default":
+        server:
           host: "127.0.0.1"
           port: 4317
         auth:
@@ -61,11 +62,13 @@ collector:
           key: /tmp/key.pem
           generate_self_signed_cert: true
   processors:
-    batch: {}
+    batch: 
+      "default": {}
   exporters:
-    debug:
+    debug: {}
     otlp:
-      - server:
+      "default":
+        server:
           host: "otel-collector"
           port: 4317
         authenticator: headers_setter
@@ -79,3 +82,9 @@ collector:
         - action: insert
           key: "authorization"
           value: "fake-authorization"
+  pipelines:
+    metrics:
+      "default":
+        receivers: ["otlp/default", "host_metrics", "nginx_metrics"]
+        processors: ["batch/default"]
+        exporters: ["otlp/default", "debug"]