Gerrit offline reindexing ignores persistent cache implementation
provided as libModule and always generates caches using H2
implementation. This fix allows to use a different persistent cache
backend.
Using different cache implementation during the offline reindexing
and at runtime causes situation when Gerrit starts without any
precomputed caches which significantly impacts overall performance.
On the other hand offline reindexing cannot reuse existing caches
which impacts reindexing performance.
Bug: Issue 13464
Change-Id: I36305282e8ea583dfb37f629e41d219762c3b4a3
cfab48793a