Helm Chart: Do not set agent key secret in values

[karrth]

I was able to avoid committing our agent key to our version controlled kubernetes configuration by overriding the key location variable and providing a false value in logdna.key, following the older v2 documentation:

  values:
    logdna:
      key: 'true'
    extraEnv:
      - name: LOGDNA_AGENT_KEY
        valueFrom:
          secretKeyRef:
            name: logdna-agent-key
            key: logdna-agent-key

While I understand requiring the key for the daemonset ot be spawned, I'm not sure why you'd deploy this chart unless deploying the daemonset is your objective. Ideally, one could specify the secret to be used for value retrevial, and the chart wouldn't try to create a secret if that value is specified. One way would be to:

1. Removing this if statement from the beginning of daemon_set.yaml: {{- if .Values.logdna.key -}}
2. Set an if statement around the secret creation to not create it if the LOGDNA_AGENT_KEY env variable exists

[inductor]

This is very important... please do not ignore :(