[OSS] Remove Requirements on Role for OnCall users

[FecoDoo]

What would you like to see!

Hey, we noticed that with Grafana OSS and Grafana OnCall OSS, Grafana users must have either Admin or Editor roles in order to be able to join shifts. The issue is we cannot assign roles with Terraform resource grafana_role_assignment which tries to call the /access-control/roles/{roleUID}/assignments endpoint which does not exist in Grafana OSS. Hence, we need to manually update user roles in Grafana UI to assign basic roles needed for them.

We are eager to know if there's a walk around to somehow remove such RBAC constraint for oncall users, or auto assign basic roles to oncall users when they join shifts.

Product Area

Other

Anything else to add?

No response

[github-actions]

The current version of Grafana OnCall, at the time this issue was opened, is v1.13.9. If your issue pertains to an older version of Grafana OnCall, please be sure to list it in the PR description. Thank you 😄!