proxy repository default negative cache size is too low to be effective

Nexus 2 had a global not found cache of 100000 entries shared across all repositories.

When we suspected large customers were overflowing this 100000 max entry limit, we would ask them to up this to 1 million and this resulted in noticeable performance improvements ( throughput)

Nexus 3 has a per repository not found cache of 1000 entries.

In the majority of cases the Nexus 3 default cache size is too low and forces Nexus to go remote more often than desired.