Increase the size of the security cache to improve performance

This value could be adjusted in infinispan configuration, but most user don't take care and the current size is really small, only adapted for a small single wiki.

Since increasing the number of entries from 500 to 10k will have a memory footprint estimated to only a few megabytes at most, and eviction of security entries could quickly decrease the performance of the security cache (removal operations are costly in terms of locks), I am increasing the default size of the security cache to 10k entries.