Adding events doesn't work with security plugin enabled

[joshuali925]

Describe the bug
After enabling security plugin, all events goes to global tenant regardless of the current tenant

To Reproduce
Steps to reproduce the behavior:
go to admin private tenant
create a channel first
create an event using send test message

GET /_plugins/_notifications/feature/test/<channel-id>
response:
{
  "event_id" : "<event-id>"
}

query the event id, see error

GET /_plugins/_notifications/events/pOrN7noBi0kFiZoXkBqz
response:
{
  "error" : {
    "root_cause" : [
      {
        "type" : "status_exception",
        "reason" : "Permission denied for NotificationEvent pOrN7noBi0kFiZoXkBqz"
      }
    ],
    "type" : "status_exception",
    "reason" : "Permission denied for NotificationEvent pOrN7noBi0kFiZoXkBqz"
  },
  "status" : 403
}

and switch to admin global tenant, the same event API works.
Configs (channels, senders, email groups) are working as expected.

---

Expected behavior
A clear and concise description of what you expected to happen.

Plugins
Please list all plugins currently enabled.

Screenshots
If applicable, add screenshots to help explain your problem.

Host/Environment (please complete the following information):

• OS: [e.g. iOS]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.

[joshuali925]

closing since we support backend roles instead of tenants now