secretRef without key does not fail the config generation

[a-thaler]

Description
When creating a LogPipeline using secretRefs without specifying a key, the pipeline gets accepted and the "ConfigurationGenerated" status gets true. Later on the log delivery fails as no authorization is provided..

Example pipeline:

apiVersion: telemetry.kyma-project.io/v1alpha1
kind: LogPipeline
metadata:
  name: test
spec:
  input:
    application:
      containers:
        exclude:
        - istio-proxy
      keepOriginalBody: true
      namespaces: {}
  output:
    http:
      dedot: true
      host:
        valueFrom:
          secretKeyRef:
            key: ingest-endpoint
            name: cls
            namespace: observability
      password:
        valueFrom:
          secretKeyRef:
            key: ingest-password
            name: cls
            namespace: observability
      tls: {}
      uri: /customindex/kyma
      user:
        valueFrom:
          secretKeyRef:
            name: cls
            namespace: observability
status:
  conditions:
  - lastTransitionTime: "2024-10-08T15:33:37Z"
    message: Fluent Bit agent DaemonSet is ready
    reason: AgentReady
    status: "True"
    type: AgentHealthy
  - lastTransitionTime: "2024-10-08T15:34:47Z"
    message: LogPipeline specification is successfully applied to the configuration
      of Fluent Bit agent
    observedGeneration: 2
    reason: AgentConfigured
    status: "True"
    type: ConfigurationGenerated
  - lastTransitionTime: "2024-10-08T15:36:18Z"
    message: 'Backend is not reachable or rejecting logs. All logs are dropped. See
      troubleshooting: https://kyma-project.io/#/telemetry-manager/user/02-logs?id=no-logs-arrive-at-the-backend'
    observedGeneration: 2
    reason: AllTelemetryDataDropped
    status: "False"
    type: TelemetryFlowHealthy
  unsupportedMode: false

In the status you see that the configuration is accepted by the telemetry-manager.
I would expect the validation to fail as a "secretKeyRef" without key is meaningless.

Please also verify that the other pipeline types are working as expected.

I observed another scenario where the referenced secret got deleted after the pipeline was running, now the LogPipeline continues to push to a non-existent endpoint instead of failing with configuration problems. Please validate this scenario as well.