Evict from cache as late as possible in race test.
Exact number of relationships given node label.

The CountsStore maintains the exact number of relationships in the
database that either starts or ends in a node with a given label. Counts
are maintained both in total, and by relationship type, but only for one
label, i.e. number of relationships that starts in a node with a given
label and ends in a node with a given label is not maintained.
Merge pull request #3094 from thobe/2.2-counts-store

Number of relationships given node label.