Errors in the collector when configuring Prometheus as the receiver and Data Prepper as the exporter.

I configured the opentelemetry collector with Prometheus as the receiver and data prepper as the exporter. However, I'm encountering no error in the collector, and no data is showing up in the OpenSearch dashboard. What should I do? What might I have done wrong?
I'll attach the Data Prepper configmap YAML and the OpenTelemetry Collector configmap YAML below.

[data prepper configmap yaml]

    otel-metrics-pipeline-2:
      #      workers: 5
      delay: 10
      source:
        http_source:
          ssl: false
          port: 21891
      buffer:
        bounded_blocking:
          buffer_size: 12800
          batch_size: 1024
      sink:
        - opensearch:
            hosts: ["https://opensearch-cluster-master.opensearch.svc:9200"]
            insecure: true
            username: admin
            password: admin
            index_type: custom
            index: proms-%{yyyy.MM.dd}

[otel collector configmap yaml]

data:
  relay: |
    exporters:
      debug: {}
      logging: {}
      otlp/metrics:
        endpoint: data-prepper-headless.opensearch.svc.cluster.local:21891
        tls:
          insecure: true
    extensions:
      health_check:
        endpoint: ${env:K8S_POD_IP}:13133
    processors:
      memory_limiter:
        check_interval: 5s
        limit_percentage: 80
        spike_limit_percentage: 25
    receivers:
      prometheus/internal:
        config:
          scrape_configs:
          - job_name: apps
            kubernetes_sd_configs:
            - role: pod
              selectors:
              - role: pod
                # only scrape data from pods running on the same node as collector
                field: "spec.nodeName=${NODE_NAME}"
            relabel_configs:
            # scrape pods annotated with "prometheus.io/scrape: true"
            - source_labels: [__meta_kubernetes_pod_annotation_prometheus_io_scrape]
              regex: "true"
              action: keep
              # read the port from "prometheus.io/port: <port>" annotation and update scraping address accordingly
            - source_labels: [__address__, __meta_kubernetes_pod_annotation_prometheus_io_port]
              action: replace
              target_label: __address__
              regex: ([^:]+)(?::\d+)?;(\d+)
              # escaped $1:$2
              replacement: $$1:$$2
            - source_labels: [__meta_kubernetes_namespace]
              action: replace
              target_label: kubernetes_namespace
            - source_labels: [__meta_kubernetes_pod_name]
              action: replace
              target_label: kubernetes_pod_name
          - job_name: 'otel-collector'
            scrape_interval: 5s
            static_configs:
            - targets: ['prometheus-k8s.monitoring.svc:9090']
            metric_relabel_configs:
              - source_labels: [ __name__ ]
                regex: '.*grpc_io.*'
                action: drop
      otlp:
        protocols:
          grpc:
            endpoint: ${env:K8S_POD_IP}:4317
          http:
            endpoint: ${env:K8S_POD_IP}:4318
    service:
      extensions:
      - health_check
      pipelines:
        metrics/internal:
          exporters:
          - debug
          - logging
          - otlp/metrics
          processors:
          - memory_limiter

Review the attached Data Prepper and OpenTelemetry Collector ConfigMap YAML, starting with the receiver/exporter endpoint and metrics pipeline wiring. Reproduce the Prometheus-to-Data Prepper path and inspect collector, Data Prepper, and OpenSearch output. Done means identifying the configuration issue and documenting the settings needed for metrics to appear.