Reduce number of user roles

[dennis531]

Some of our users are assigned many user roles by the user provider. One user has 4106 roles, which leads to problems in Opencast, e.g. stackoverflow problems due to very long query DSL statements. This causes failures during video uploads, for example.

The number of roles should be optimised to a minimum. Here are some statistics from a user with many roles and OC problems:

Total roles 4106 including:

• <video-id>_write: 1132 (unused roles due to oc episode acls)
• ROLE_EPISODE_<video-id>_READ: 1159
• ROLE_EPISODE_<video-id>_WRITE: 1131
• <video-id>_read: 605 (unused roles due to oc episode acls)
• <course-id>_Instructor: 67
• <course-id>_Learner: 12
• PLAYLIST__write: 1 (broken role)
• PLAYLIST__read: 1 (broken role)

-> 1739 roles can be simply reduced