Problem:
- Grafana can't mount PV correctly in Cloud

Solution:
- Use SecurityContext

Issue:
rancher/rancher#16953

        (+) Only use for Rancher 2.0 Monitoring and Alerting
        (+) Support Grafana to proxy with authorization bearer token to
        Prometheus-Auth agent
        (+) Support Prometheus web to proxy with authorization bearer token
        to Prometheus-Auth agent
        (+) Rich metrics for Kubernetes and Rancher
Co-authored-by: aiwantaozi <michelia.feng@gmail.com>
Co-authored-by: orangedeng <jxfa0043379@hotmail.com>