FIX(otel): add scrape_configs for Target Allocator

- Add minimal scrape_configs (required by Operator)
- Keep self-metrics scraping alongside Target Allocator

opentelemetry-collector/manifests/collector.yaml

@@ -165,6 +165,11 @@ spec:
         config:
           global:
             scrape_interval: 60s
+          scrape_configs:
+            - job_name: otel-collector
+              scrape_interval: 60s
+              static_configs:
+                - targets: ['${env:K8S_POD_IP}:8888']
         target_allocator:
           endpoint: http://otel-collector-targetallocator:80
           interval: 30s