Fix for mount permissions on the agents PV

[dannyzaken]

Explain the changes

• Fix for mount permissions
  • For some reason, the changes in SCC fixes #1340 caused the PV to be mounted without write permissions for GID 0 and be owned by root user.
  • Added fsGroup 0 to the agent pod. This adds w permission to the mount for the owning GID 0 and provides write access to the agent process.
• Also moved allowPrivilegeEscalation in the DB sts to the container security context
  • This setting can only be set in the container security context, not the pod security context. (see here)

Issues: Fixed #xxx / Gap #xxx

1. Fixes https://bugzilla.redhat.com/show_bug.cgi?id=2278120

Testing Instructions:

1. Create a pv pool on an openshift cluster
2. Make sure it runs successfully
3. The issue is not reproducible on minikube\rancher, since the pv is mounted there with 777

• Doc added/updated
• Tests added