Rename the qpzone and qpcache methods that implement DB api

Rename the qpzone and qpcache methods that implement DB api

All the database implementations share the same names for the methods
implementing the database.  That has some advantages like knowing what
to expect, but it turns out that any time such method shows up in any
kind of tracing - be it perf record, backtrace or anything else that
uses symbol names, it is very hard to distinguish whether the find()
belongs to qpcache, qpzone, builtin or sdlz implementation.

Make at least the names for qpzone and qpcache unique.