[Improvement] redis remove the agamotto image

[ldming]

Remove the agamotto image that is deprecated.

metrics:
  image:
    # if the value of metrics.image.registry is not specified using `--set`, it will be set to the value of 'image.registry' by default
    registry: ""
    repository: apecloud/agamotto
    tag: 0.1.2-beta.1
    pullPolicy: IfNotPresent
  service:
    port: 9121
    serverPort: 8888

[shanshanying]

we can enable the addon with `enableMetrics=false'

[shanshanying]

and we will replace agamotto with redis exporter