[Access Control] Fix performance issues with Redis SCAN

[JulienDuf]

The default page size of a scan is small, 10 with my current setup.

This can cause performance issues with large Redis Databases, it will create a lot of iteration with the cursor. In some cases, it more performant to process larger pages.

[Jtplouffe]

I think 10k might be too much, we should probably consider something like 500 or 1000, otherwise it may block the redis server for too long, and may stack up pending commends