Improve scalability of site-node caches
Some sites have site-node caches with more than 200k site-node entries.
Wild card operations for flushing in these caches can take a while (2-digit ms),
locks on the site-node cache can lock everything. This change separates
the caches with wild-card operations from the parts not requiring these.
improving vor sample data the scalability at least by a factor of 4.
